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By V. Madhusudhan Rao

Fly ash is a finely divide non ? combustible material obtained as a by ? product of coal combustion. It is a major by ? product of coal based thermal power stations. Until recent past it was considered as a waste and highly polluting material. However its formation can only be minimized by using suitable technology in the boilers. In recent past it is found that Fly ash has many end uses and it has proven itself to be a potential construction material. But the suitability of fly ash for various applications largely depends on the amount of unburned carbon, which is turn depends on the firing method. Fly ash samples from various power plants existing in India using a fluidized bed method and pulverized bed were analyzed and a comparison of these two firing methods was carried. This paper deals with the compositional requirements for fly ash used for the fabrication of insulating doors using AAC (Aerated Autoclave Concrete) and the methods employed to make fly ash suitable for this purpose. It also includes the latest ?U? beam technology for effective fly ash recycle. If the by products of coal combustion from power plants like fly ash as the paper stresses are utilized properly, it is not an exaggeration to say that power generation is possible with absolutely zero cost.

Jan 1, 2006

By Jamil M. Khalifeh, Shadia J. Ikhmayies, Bothina A. Hamad

"The structural and electronic properties of cubic d -NbN are investigated using density functional theory (DFT) and all-electron full potential linearized augmented plane wave method (FPLAPW). The equilibrium structural parameters are determined by fitting the total energy as a function of volume to the Murnaghan's equation of state. We calculated the total and partial densities of states (DOS) and compared them with those computed by different authors. Our DOS at Fermi level is found to be very close to the experimental value. The band structure is computed, discussed and used to find the characteristic energy separations. Valence electron density contours are recorded and discussed. We deduced the partial charge densities of different bands and binding energies of valence core levels and compared them with experimental and theoretical results obtained by different authors.IntroductionNiobium nitride has been intensively investigated over the last decades because of its interesting physical properties and technological applications (superconducting microdevices, microelectronic, catalytic probes, and hard coatings) [l]. While the group IV transition metal nitrides (TMN) mainly crystallize in the cubic NaCl structure (Bl type), those of group V and VI nitrides occur as different phases. Thus for niobium nitride, many phases have been reported in the literature: cubic fcc d -NbN, tetragonal ? -Nb4N3, hexagonal d -NbN, hexagonal e -NbN, and low nitrogen content hexagonal ß -Nb2N [l, 2].Structural and electronic properties of niobium nitride were investigated theoretically and experimentally by many authors. For example, in 1975 Schwarz [3] obtained the partial density of states for NbC and NbN from APW band structure calculations. In 1975 Kallne and Pessa [4] studied the electronic structure of Nb, NbC and NbN by using X-ray emission. In 2003 Amriou et al. [5] studied the electronic structure and bonding mechanism of NbC and NbN compounds using first principle total energy calculations using the full-potential linearized augmented plane wave method. Also in 2006 Sanjines et. al [l] studied the electronic structure of the hexagonal~Nb2N, hexagonal' d -NbN, and cubic d -NbN thin fihns by using X-ray photoemission spectroscopy. They [l] also calculated the densities of states for these phases and used them in the interpretation of the experimental valance band spectra. Most of these studies are old and there is a need for more recent studies. According to our knowledge, there are little comprehensive theoretical studies on this subject by using FP-LAPW method [5], which proved its ability to give accurate results. In this work we used the FP-LAPW method to study the structural and electronic properties of the cubic (fee) o-NbN (space group Fm-3m, prototype NaCl) crystal."

Jan 1, 2013

By Wen-Ming Chien

Low temperature X-ray diffraction and thermal property studies of the solid-solid state phase transition for the polyalcohols (pentaerythritol (PE), pentaglycerine (PG) and neopentylglycol (NPG)) thermal energy storage solid solutions have been investigated by using X-ray diffractometry and differential scanning calorimetry (DSC) methods. X-ray diffraction studies on polyalcohols solid solutions, PE-NPG and PG-NPG, are from ?10oC to 50oC. XRD results shows the + mixed phase at the related low temperature (?10oC) for both PE-NPG and PG-NPG solid solutions. At high temperature range, XRD results show phase for PG-NPG solid solution and + mixed phase for PE-NPG solid solution. There are only two Bragg peaks, (111) and (200), shown in phase XRD patterns. The polyalcohols solid solutions have been cycled 5 times between -20oC to 100oC at different DSC scan rates to study the phase transition properties. DSC results of both PE-NPG and PG-NPG solid solutions show that the solid-solid state phase transition is near room temperature. Details of low temperature phase transition XRD and DSC results of PE-NPG and PG-NPG solid solutions will be presented

Jan 1, 2006

By Raj Mutharasan

The phenomena of gas-molten metal reactions for the production of metal matrix composites consist typically of a combination of one or more gas transport steps and a liquid gas reaction step. Reaction products include such strength enhancers, grain refiners, or high thermal conductivity phases as TiC, AIN, SIC, Si3N4, TiN in aluminum alloys. Nitrides, carbides and oxides can be produced at various volume fractions and in fairly fine sizes (500 am to 5 um) in laboratory melts by Reactive Gas Injection method (RGI). Gas injection methodology to produce the reinforcements is attractive because it can potentially be scaled to production scales in excess of 10,000 kg/h. For continuous production, the reactant molten metal can be continuously fed into the .crucible where the reactive gas is injected. The molten metal phase reactant may also be involved in a controlling transport step, depending on its concentration and viscosity. It is well known that the reaction product reinforcement size and shape of these phases have significant impact on the physical, mechanical and thermal properties. The current state of knowledge is unable to predict the kinetics and growth of solid reaction products obtained. The primary goal is to develop a fundamental framework for the understanding and prediction of the particle size in such reaction systems. In addition, the role of gas transport, liquid hydrodynamics and decomposition are important issues. A reaction-transport model is being developed using a reaction, transport, and thermodynamic framework, both at macro and at atomistic level to assess gas - liquid interactions.

Jan 1, 1996

By Alice Barreto Bevitori, Frederico Muylaert Margem, Noan Tonini SImonassi, Caroline Oliveyra, Sergio Neves Monteiro, Isabela Leão Amaral da Silva

"The mechanical behavior and the fracture characteristics of composites with DGEB/TETA epoxy matrix reinforced with up to 30% in volume of continuous and aligned ramie fibers were evaluated by tensile tests. Specimens with selected thin fibers aligned along the tensile axis were room temperature tested to rupture. The fracture surface was analyzed by scanning electron microscopy. The results showed significant increase in both the ultimate tensile strength and the elastic modulus. The fracture analysis indicated the possible mechanism for the fiber/matrix interaction, which could be responsible for the composite performance.IntroductionSince the middle of last century, polymer composites have substitute many conventional monolithic materials in applications ranging from aerospace to sport [l]. The main advantages of these composites are the low density and flexible properties specially using fiber as reinforcement to suit the mechanical performance requirements [2]. These are usually high strength and stiffuess requirements that could be reached with synthetic fibers such as gloss, carbon and aramid fibers. Its most commonly used example is ""fiberglass"", i.e., a thermoset polymer matrix composite reinforced with glass fiber. Indeed, ""fiberglass"" has a specific strength of the order of 500 MPa.cm3/g, which is the double of the strongest steels like the maraging. This motivated, at earlier times, ""fiberglass"" to replace many conventional materials including wood and natural fiber composites. Today, ""fiberglass"" has a wide range of uses from aerospace systems and appliances to sport and leisure components. However, its fabrication as well as those of any synthetic fiber such as carbon and aramid composites, requires a relatively large amount of energy. Presently, a growing concern exists regarding the consequences to the environmental by gases like C02 associated with both the energy consumption and the processing of synthetic fibers and their composites. These gases are well known responsible for global warming [3]."

Jan 1, 2013

By B. R. Baldock, R. W. Matusewicz

The recycling of used computer boards is a key industry activity for the recovery of precious metals. The safe and effective separation of metallic from non-metallic materials and subsequent processing of these secondary materials to provide high recoveries of values and excellent environmental performance are critical process requirements. Ausmelt Technology has been used commercially in four plants for the recovery of precious metals and has also been used very successfully at pilot plant scale to process computer boards. This work and its application to commercial operations with particular reference to processing conditions and environmental performance are reviewed.

Jan 1, 2000

By A. V. Tarasov

The high efficiency of autoclave processes is attributed to the fact that they are suitable for processing of refractory raw materials, have low capital costs and high productivity, ensure integrated utilization of the feed materials, produce innovative saleable products, completely eliminate any air emissions, provide low-waste or waste-less technology, as well as mechanization and automation of production processes. In the immediate future, it might be expected that autoclave processes will find use on commercial scale for production of heavy non-ferrous metals in combination with other processes (hydrometallurgical, upgrading, sorption and solvent extraction, electrolytic, etc.) to ensure: -Integrated processing of refractory ores and concentrates (pyrrhotite, zinc, copper-zinc, lead-zinc, nickel-cobalt, copper, pyrite); -Production of metallic powders of base metals as commercial products (copper, cobalt, nickel, etc.), composites on their bases, final products and saleable salts. Processing technologies incorporating autoclave processes, especially, at the stage of liberation (chemical upgrading) of minerals, are characterized generally by high overall recoveries of valuable constituents significantly exceeding recoveries common for conventional pyrometallurgical processes (for some elements by several tens of percent). An example is processing of low-grade refractory pyrrhotite concentrates using autoclave liberation of feed material under pressure of a new reagent, i.e., sulfur dioxide. The use of sulfur dioxide ensures a significant improvement in the recoveries of non-ferrous metals and platinoids to sulfide concentrate and smelting of the latter increases the capacity of the smelting units employed and minimizes the yield of discard slag and loss of metals in slag; in addition, it resolves the problem of sulfur dioxide utilization.

Jan 1, 2003

By Y. W. Miao

Along the south-west coast of Taiwan is about 550,000 metric tons of heavy sand deposit containing about 10 % black monazite. The Institute has developed a separation process to recover the individual rare earths and the developed process has been commercialized by a local private company. The decomposition of the local black monazite by sodium hydroxide through hydrothermal and fusion methods has been investigated. In the hydrothermal process 4.5 wt. % of aqueous alkali solution was used in an autoclave. In the fusion process, caustic soda (9.8% NaOH) was employed in am open cylindrical reactor. The same product of hydrous rare earth oxides were obtained and then dissolved by hydrochloric acid and the p-H adjusted in order to separate the thorium from the rare earths. After filtration, the filtrate contained rare earth chloride and the cake contained mainly the silica and thorium hydroxide. Both methods give a yield of 90 % with respect to the rare earths recovery. A detailed description of operation and comparison of the two methods are given.

Jan 1, 1989

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Jakub Kaczorowski

In the production of Mn-alloys, the Boudouard reaction significantly influences the mass and energy balance. The endothermic nature of this reaction requires more energy for the process, while the direct consumption of carbon is reflected in the greater demand for carbonaceous raw materials. Therefore, it is desirable to eliminate or suppress the reaction. The kinetics of the Boudouard reaction are a function of many factors, of which coke properties and the conditions around the particles (i.e. temperature, gas composition) seem to be the most important. In the present study properties of selected single source and commercial metallurgical cokes are compared with reactivity results. The single source cokes represent a single coal that has been carbonized in a laboratory scale furnace. The commercial cokes are products of carbonization of coal blends under industrial conditions. The coke properties include proximate, ultimate and ash analysis. Also, coke petrography with carbon forms is included. The reactivity tests were performed on different particle sizes at various temperatures, gas compositions and gas flow rates. The experimental parameters were chosen to simulate the conditions in an industrial furnace. The results show that highly graphitized structure of cokes, minimal surface area and a low concentration of ash retard the reactivity. Of the other factors, the temperature and the gas composition have the greatest impact on the reactivity.

Jan 1, 2006

By J. E. Jacoby

Scrap recycling has become an increasingly important source of metal units for the aluminum industry during the past 25 years. Aluminum scrap from the manufacture and recycling of cans, automobiles, buildings and other products has created an industry that melts these products and delivers the metal in molten or sow form to companies that make cast parts or fabricated products This rapidly developing recycling industry has contributed a large number of severe (Force 3) molten aluminum explosions (25) with associated fatalities (19) to the Aluminum Association data accumulated during the past nineteen years. The explosions that occurred in recyclers plants represent 17% of the total explosions, 33% of the Force 3 explosions and 37% of the fatalities reported. These explosions can be prevented! This paper will identify causes of these explosions and procedures that can be used to prevent them.

Jan 1, 2000

By Keri Ledford, Stephanie Lin, Jason Nadler

Novel processes are being developed to fabricate thin copper thermal wick samples of a targeted porous microstructure. Structures of desired porosity, thisckness and pore size and distribution are achieved by tayloring the incorporation of sacrificial polymer beads in to slurry precursors. The thickness of the final structure is dictated by precisely controllable slurry application methods, such as spin coating. Ina subsequent heat treatment, th epolymer components thermally decompose and the remaining copper particles sinter to form a reticulated foam. The resulting microstructures are characterized in terms of porosity, permeability and specific surface area.

Jan 1, 2012

By Jean-François Domgin

This paper aims at presenting numerical results showing the impact of different parameters on the limitation of entrained slag from ladle to tundish during the ladle drainage. These parameters are process parameters, slag properties or external actuator acting directly on ladle slag behaviour. Numerical simulations based on the use of the CFD Fluent software illustrate the vortexing and non-vortexing phenomena appearing during the ladle drainage. This numerical tool validated by experimental data acquired on water model has been applied to industrial configurations. It shows that the slag properties (viscosity, surface tension?) or some modifications of parameters (slide gate opening, geometry of the ladle bottom?) have a positive effect on the slag entrainment and also on the decrease of the ladle heel. Finally, the modelling of the behaviour of an external actuator injecting some gas in the region of the nozzle reveals interesting possibility for reducing slag entrainment from ladle to tundish during the final steps of the drainage.

Jan 1, 2006