Search Documents

By Neale R. Neelameggham

"Most chemical process plants and metallurgical production facilities have some sort of cogeneration to minimize process energy costs. Use of Alternative Energy Production from sun and wind power with storage can become an integral part of a process plant utility. This will facilitate reduced fossil fuel usage and help minimize thermal emissions. This will be similar to Pollution Control equipment, which have become an essential part of process plants in the past four decades. Conceptual flow sheets of such Process Utility schemes are presented.IntroductionPower is supplied to industries, commercial and residential users. Over the past decade, Electric Utility companies have made major inroads, in introducing alternative energy resources in an attempt to somewhat reduce fossil fuel use in power generation. Now, on a much larger scale than in the early 1980s, residential users, motivated by government provided tax credits, have started installing alternative energy generators such as roof top wind mills or roof-top photovoltaic generators. This will minimize future energy costs, help control thermal emissions etc. This alternative power generation is typically connected to the existing power grid with two way power metering. However, the use of alternative energy generation has not been seen at large industrial sites yet.Paul Scherer Institute, Switzerland and the NREL laboratories in Colorado, are two of the several institutes which have been developing how solar thermal power can be used to supply the endothermic input energy in chemical and metallurgical processes. The theme of this present symposium addresses the above as well as the energy storage needs for such events to become continuous. This paper emphasizes the concept of how alternate energy can be used in the production of materials on a generic sense wherever there is a need for input energy – beyond endothermic process energy - while addressing how to reduce the thermal and carbon emissions.The alternative energy generation using wind or solar source is discontinuous due to the nature of the energy source. They are not only discontinuous but also variable. This necessitates storage of generated power for close to continuous use with variable loads. C Smith, et al pointed out in 2006, that 'the electric power industry has taken notice of the expansion of wind and its potential' in a summary article on integrating wind generation into utility systems.1 In 2009, the 1000 MW wind generation project in Texas had to be postponed to 2013 for lack of transmission.2 There are only a few large MW solar generation units in the US; the projects being slow mainly from lack of adequate storage and redistribution."

Jan 1, 2010

By Saeid Pournaderi, Ahmet Geveci, Ender Keskinkilic, Yavuz A. Topkaya

"This study investigated calcination behavior of one of the Turkish laterite deposits, which was recently found in Sivrihisar region. Representative limonitic laterite samples (1.26% Ni) taken from Yunusemre Karasivritepe and Kucuksivritepe location were first subjected to drying. Removal of chemically bound water and other volatiles were then studied, in detail. In the calcination experiments, temperature and time were the main experimental variables. Thermal treatment was conducted at the specific temperatures in 250 °C - 800 °C range. The weight losses due to elimination of chemically bound water and other volatiles were reported to be approximately 10 per cent of the weight of the ore. For the particle size used in the current work, 700 °C and 40 minutes were determined to be the optimum calcination temperature and time, respectively.IntroductionThe nickel ores that are economically valuable can be grouped into two categories: sulphide type nickel ores and oxide type nickel ores, namely laterites. Over all reserves in the world, 40% are sulphide nickel ores and the remaining 60% are laterites [1]. Pyrometallurgical nickel extraction from sulphide type nickel ores is conducted via matte smelting. More recently, laterite ore bodies have been subjected to nickel extraction. Depending mainly on the chemical composition of the laterite and the process economics, various extraction techniques have been implemented: pyrometallurgical route involves ferronickel smelting. High pressure acid leaching (HPAL) is the commercial method for hydrometallurgical nickel extraction, while ammonia leaching (CARON Process) is a combination of pyrometallurgical and hydrometallurgical processes [2]. With the improvements in these processes, it is predicted that laterite’s share in the world nickel production will rise to 50% in 2012, while it was reported to be 42% in 1,200,000 tons of annual production in 2003 [3]."

Jan 1, 2011

By P. A. Mahanwar

Flyash were melt mixed with nylon 6 at a 30wt% concentration. TYZOR® TPT, a coupling agent, was used to facilitate the link between filler and matrix. The morphological characterization, using SEM, revealed sufficient matrix residue on the filler surfaces thus confirming the strong interfacial bonding between the filler and the matrix on treating. Tensile, impact and the flexural properties of the composites were also improved with the incorporation of coupling agent. As flyash particles tend to impart a grayish color to the plastic, TiO2 pigment was employed to make the formulations aesthetic. The pigment was added to the filled system in 0.1, 0.5, 1.0, 1.5, 2.0 wt/wt ratios. Scattering of incident light and spectral reflectance was higher for smaller particle size flyash. Moreover an increase in the scattering with increase in pigment concentration indicates better dispersion of the pigment, which again is due to the presence of coupling agent.

Jan 1, 2006

By Takashi Miyamoto, Hideo Nakae, Hideki Yamaura, Takeshi Yanagihara

"For the production of partially composed metal matrix composites, namely discontinuous MMCs, using a casting· process, the interpenetrated phase composites with SiC particles were fabricated by pressureless iDfiltration using molten Al-Si alloys. This process is based on a wetting phenomenon, therefore, we discussed the technique based on the reactive wetting. The SiC particles coated by diluted water glass were sintered in a mullite Tammann tube and simultaneously infiltrated with molten Al-Si alloys in air at 1173~1573K. As for the improvement of the wettability between the SiC and the liquid aluminum alloy, Fe3O 4 powder was mixed with the water glass due to the thermit reaction between Fe3O4 and molten aluminum alloy. In some experiments, pure aluminum powder was placed on the sintered SiC to increase the interfacial area and the chemical reaction between the sintered Sic. and the melt. By combining these conditions, we succeeded in the complete infiltration without pressure at 1173K.IntroductionAs is well known, the mechanical properties of metal matrix composites (abbreviated MMCs) are superior than that of ordinary metals. However, their use has not been widely accepted because the production cost is very high due to their poor machinability. Therefore, the production of partially composed, namely discontinuous MMCs, by as the Lanxide process [l,2] has been investigated for many years. The Lanxide process, it takes a long time, sometimes up to 10h, in a nitrogen atmosphere for the infiltration. Therefore, the cost will be higher for common use. On the other hand, a high 'pressure process has been adopted for the production of discontinuous MMCs by the Toyota Motor Corp.[3]."

Jan 1, 2000

By K. G. F. Janssens

In the process of annealing a deformed metal the microstructure changes due to concurrent recrystallization, grain growth and precipitation. It is common knowledge that all three of these microstructural transformations show a strong dependence on each other, and that an overall model must take the relevant interactions into account. Aiming at the development of an approach which is useful in the more general case, a computational model is being developed which allows the prediction of the three dimensional grain topology and orientation distribution function of any metal submitted to subsequent deformation and annealing, taking into account concurrent recrystallization, grain growth and precipitation and starting from a statistical representation of the deformed microstructure. In this contribution a case study is presented which illustrates the potential and limits of the state of the art in the field. Keywords: Microstructure Evolution Modeling, Irregular Cellular Automata, Deformation, Precipitation, Recrystallization, Grain Growth

Jan 1, 2003

By Guo Xian Jian

In this paper, the effects of matte grade, flux grain size, blast flowrate and blast O2 content on the process of silica flux melting in a copper converter were investigated. The results showed that the blast flowrate and the blast 02 content were not significant factors in the melting process. However, with an increase in grain size of flux and grade of matte, the amount of the flux molten decreased. The data on the melt rate of process correspond well with the mathematical model which simulates the chemical reactions occurring at the interface. The kinetic equations of melting are as follow:

Jan 1, 1996

By Abhishek Asthana

The incineration of Municipal Solid Wastes (MSW) is an attractive process for reducing the volume of the wastes and recovering their energetic value, which, however, requires to be strictly controlled in order to limit its impact on the environment. In this context, we have undertaken the mathematical modeling of the different sections of a typical incineration plant. The combustion of the waste bed, usually carried out on a moving grate, is at the core of the process. This paper presents the 2-dimensional, steady-state model that we have developed for simulating the MSW combustion. The model describes gas flow through the porous waste particle bed, the gas-solid reactions, conductive and radiative heat transfers, drying of the feed, its pyrolysis and the emission of volatile species, combustion of the pyrolysis gases, the formation of char and its gasification by water vapor and carbon dioxide, and the consequent reduction of the bed volume. Pyrolysis kinetics distinguish between cellulosic and non-cellulosic materials and are experimentally derived from our laboratory measurements. The calculated results give a deep insight into the various involved phenomena, an example being the complete consumption of oxygen in a large zone of the bed and the related appearance of a char gasification zone. The influence of various operating parameters, like the temperature and flow rate of primary air, is presented and explained. Finally, the effect of stirring the waste bed on the moving grate is also analyzed.

Jan 1, 2006

By Ki Bui Ma

Momentum wheels with superconducting bearings can integrate both attitude control and energy storage functions, with attendant savings in the total volume and weight of hardware, and power consumption, all of which are in short supply on mini-satellites. We have built and tested a prototype with a wheel of mass 1.9 kg, diameter 3.25 in, and height 3 in, which can store 3.5 J-sec of angular momentum and 5 kJ of energy when it rotates at an angular speed of 15000 RPM. The energy density of 2.5 kJ/kg achieved is comparable with the lower range for lead-acid batteries. To show that the wheel is energy efficient, we have performed spin down tests and measured the input power required to sustain rotational speed. Results indicate that power consumption, even accounting for the needs of cooling system, is significantly smaller than that for state of the art commercial reaction wheels.

Jan 1, 2002

By V. P. Bystrov

Vanyukov process has been developed and investigated in Russia over the last 25 years. It has been established that various kind of material could be treated in Vanyukov process. The results of the pilot plant trials as well as industrial experience are presented in this paper.

Jan 1, 1993

By Kikuo Okuyama, I. Wuled Lenggoro, Manabu Shimada

"Aerosol processing of materials such as (i) gas-to-particle conversion process (e.g., Chemical Vapor Deposition (CVD) method) and (ii) liquid (or droplet)-to-particle conversion process (e.g., spray pyrolysis) has become of major interest to produce novel submicron- or nanometer-sized particulate material used in electronic and chemical industries. After reviewing recent theoretical and experimental researches on the evaluation of properties and morphology of fine particles by the CVD and spray pyrolysis methods, the importance of the process engineering approach· for aerosol processing of materials and the use of advanced aerosol measurement technology have been pointed out.IntroductionMaterial synthesis via aerosol processing offers a route to producing nanometer-sized and submicrometer-sized particles of high purity with specifically tailored chemical and physical properties. Especially, single nanometer-sized particles (nanoparticle materials) are considered to play an important role in the synthesis of nanostructured materials as well as in nanotechnology in 21st century due to their quantum effect and so on.However, the transformation of gaseous or liquid precursors to the final functional particulate matters consists of various complex chemical and physical processes. In order to control the size distribution and morphology of produced particles, it is important to analyze and model various phenomena, such as gas-phase or liquid-phase chemical reaction, nucleation, condensation, agglomeration and sintering that occur simultaneously in aerosol material processing. By introducing the Aerosol Science and Materials Science, the authors have been trying to model the changes in particle properties and morphology by gas-to-particle conversion and droplet-to-particle conversion processes. The authors have also been trying to obtain the experimental data on the particles properties as accurate as possible."

Jan 1, 2000

By Harovel G. Wheat

It has been shown that the incorporation of fly ash into concrete as a replacement for part of the cement can be beneficial. In some cases, the strength of the concrete can be increased and the permeability can be decreased. This latter property can lead to a reduction in the migration and/or penetration of aggressive species into reinforced concrete. Some of these species, such as chlorides from deicing salts or marine environments, can subsequently result in accelerated corrosion of the steel reinforcement, a loss of the protection provided by the passive film on steel, and a loss of structural integrity of the concrete. Care has to be taken so that the appropriate compositions of the components of the fly ash are utilized in order to ensure maximum benefit to the concrete structures. This will be discussed as it relates to fly ash generation and treatment.

Jan 1, 2002

By Elisa Alonso

Manufacturing firms that rely on finite resources have a stake in ensuring sustainable materials use. Higher material prices and uncertain material supply, consequences associated with scarcity, can be damaging to firms. Firms have a number of options to improve material sustainability including dematerialization, material substitution and recycling. However, these options require technological capability, capital investments and supply-chain infrastructure; firms may decide to make such investments only if material prices increase. Once decisions are made, the barriers and delays to implementing changes may harm firms. The impact of not reacting to changes in material supply on firms was examined for the case of different platinum-using industries. It was found that taking action is particularly important for firms when limited material availability leads to volatile market conditions. Industries can benefit especially if they ensure process flexibility and have options for changing their material use patterns.

Jan 1, 2010

By A. A. Bustos

A model was developed to simulate the blow-by-blow operation of the converting process. From the weights, compositions and temperatures of all converter feeds the model calculates the composition and tonnage of both converter matte and slag as well as bath temperature at the end of each blow. The development of the model and its application to the converter aisle operation are described. There is good agreement between model predictions and observed results. At the present time the model is being used to investigate different converting schemes and their effect on pay metal recoveries, slag chemistry and temperature of the bath. Future work involves the use of the simulation model as a process control tool for the converting operation.

Jan 1, 1988

By M. J. Collins

Direct pressure leaching of zinc sulphide concentrates was started? commercially in October 1980. Continuing research and development studies at Sherritt and feasibility studies for a number of clients have defined various pressure leach configurations for integrattons with existing roast- 1 each operations and for grass roots plants. Existing and potential applications of zinc pressure leaching are discussed.

Jan 1, 1990

By Duclerc Fernandes Parra, Washington Luiz Oliani, Christiano Gianesi Bastos Andrade, Ademar Benevolo Lugão, Danilo Marin Fermino, Francisco R. Valenzuela Diaz

This work concerns the study of the effect of discarded bond paper on the mechanical behavior of polypropylene/organophilic clay nanocomposites. A brown polycationic bentonite from the state of Paraíba, Brazil, was treated with sodium carbonate to transform it into a bentonite that swells in water and then treated with hexadecyltrimethylammonium ammonium chloride to transform it into a bentonite that swells in organic liquids. Polypropylene with 3 % polypropylene graft compatibilizer (PP-g-AM) was mixed with 1 % and 2 % by weight of discarded bond paper and with 1% and 2% by weight of organophilic clay using a twin-screw extruder. The specimens were prepared by the injection process. The clay as received and after organophilization was characterized by XRD, SEM, and capacity of swelling in water and in organic solvents. The nanocomposite specimens were characterized by XRD and thermal analysis. The mechanical behavior of the injected specimens was evaluated by strength, flexural and impact tests. The nanocomposites showed improved mechanical properties compared with the polymer without filler.

Jan 1, 2015

By R. Padilla, M. C. Ruiz

Arsenic, antimony and bismuth are commonly found in copper concentrates usually as the minerals enargite, stibnite and bismuthinite, respectively. Concentrates having high levels of arsenic and antimony must be pretreated before smelting. Roasting is the preferred method for removing these toxic impurities from concentrates; However, the removal of As, Sb and Bi in oxidizing roasting by volatilization may not be complete due to the slow reaction rates at 500- 700 °C. Oxidizing/volatilization data were obtained from pure mineral mixtures and from arsenic rich copper concentrate. The reaction mechanism for the volatilization of arsenic and antimony were discussed. Near 100% As and over 95% Sb volatilized in the oxidation of a mixture of pure minerals at 700 °C, 1% oxygen, while over 95% As, and 35% Sb volatilized at 600 °C in 1% oxygen atmosphere when using a copper concentrate containing 3.51% As, 0.14% Sb, and 0.01% Bi. Bismuth did not volatilize.

Jan 1, 2015

By Bart Blanpain, Muxing Guo, Zhuangzhuang Liu

In order to stabilize free lime in the basic oxygen furnace (BOF) slag to achieve high value products, quartz sand and other additives are injected into slag. However, the current hot stage slag stabilization does not work in case of slag (before treatment) with a liquid fraction lower than 90%, where the slag containing solid particles is too viscous. Therefore, it is essential to understand how solid phases affect the viscosity of the slag system. In this study, the industrial BOF slags were investigated with respect to the correlation between volume fraction of solid phases and its viscosity. Slag viscosity was measured with a rotating type viscometer at temperatures below the liquidus. The volume fraction of solid phases was quantitatively calculated with FactSage. The Einstein-Roscoe equation was employed to predict the viscosity of BOF slag.

Jan 1, 2016

By Shadia J. Ikhmayies

The SnO2/CdS/CdTe thin film solar cells were fabricated on glass substrates by using the spray pyrolysis (SP) technique for the deposition of the SnO2 and CdS layers and vacuum evaporation for the CdTe layer. The transmittance curves were used to investigate the interdiffusion in the two interfacial regions SnO2/CdS and CdS/CdTe by taking the first derivative of the absorbance as a function of wavelength. The appearance of new bandgaps around the bandgaps of SnO2:F, CdS:In and CdTe layers is a strong evidence on the interdiffusion in the two interfacial regions and/or the formation of quantum dots.

Jan 1, 2010

By Anna Wasilkowska

The study concentrates on the effects exerted by microstructure, deformation history and uniaxial stress conditions (temperature, stress state, strain rate) on the mechanical properties offerritic TRIP-aided steels for automotive applications. In low-alloyed TRIP-steels it is quite difficult to separate the effect of the austenite to martensite phase transformation from the influence of the ferritic matrix contributing to the yield stress and uniform elongation. Investigation of transformation kinetics of retained austenite as a function of the deformation temperature show that using the parameter k to characterize the retained austenite stability allows to identify regious of different temperature sensitivity separated by a transition temperature of 10±5°C. The observed low strain-rate sensitivity of the flow stress is an intrinsic property of the ferritix matrix and points to defomtation governed by slip. The ultimate tensile strength is much stronger affected by temperature than the yield stress. The influence of the temperature on the elongation is complex, because of the heating of the specimens by 60-l20°C at moderate and high strain rates. The increase of the total strain can be understood in terms of thermal softening of the ferrite. On the other hand, the steep increase of the stress during dynamic testing is an effect of accommodated elastic and plastic strains in the matrix. The strain- hardening exponent is dependent on the conditions imposed during testing. The martensite transfomtation rate is lower and the critical stress for martensite nucleation is much higher under compression compared to tensile loading. In secondary tensile tests, the yield stress increases steeply, and the ultimate tensile strength and the total elongation depend linearly on the amount of pre-straining. The results confirm that in the range of 8=10-4 s-l the TRIP-effect governs room temperature plasticity. Keywords: TRIP-steels, mechanical properties, strain rate sensitivity, temperature sensitivity, austenite stability

Jan 1, 2003

By Jian Zhang

From the standpoint of quality, surface cracks normally pose more of a problem than internal cracks. Hypo-peritectic (HP) steel grades are well known for their proneness to surface longitudinal cracking (SLC) during continuous casting. This study analyzed the influences of chemical composition, technique parameter and secondary cooling on the surface longitudinal cracks. Based on the optimized the first and secondary cooling zone water distribution in the process of continuous casting, low cooling water distribution at solidification initial stages and uniform cooling at secondary cooling zone were suggested, which can be used to effectively control the surface longitudinal cracks.

Jan 1, 2010