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By Joner O. Alves

The disposal of scrap tires has been a serious environmental problem. The treatment of this waste by pyrolysis and combustion has advantages since the landfill space is dwindling and the production of fuel becomes of technological interest. However, that processes needs a rigid control of emissions. This work presents a study of the light hydrocarbon gases (HC) generated during the burn of waste tire chips in a two-stage laminar-flow horizontal furnace. Different temperatures in the primary and secondary stage of the furnace were tested, and the oxygen/nitrogen percentage was also varied during the combustion process. A gas chromatograph was used to identify and quantify the components of the gaseous products of combustion and pyrolysis. The results showed the behavior of the gases during the burn of tires, providing valuable information to the control of hydrocarbon emissions.

Jan 1, 2010

By Takashi Nakamura, Kenji Oosumi, Kazuhisa Fujisawa, Takayuki Kogishi

"Recycling of used aluminum beverage cans(UBCs) is one of the important issues for aluminum manufacturer presently. The direct re-melting of UBCs shows two problems. One is a reduction in molten aluminum recovery and the other is a contamination of other metals such as Ti and Fe from paints. Both problems are caused by paints coated on the surfaces of aluminum cans. Removal technique of the paints, therefore, has been required. Although roasting and shot blast techniques have been developed, both were not successful in removing the paints effectively. A swell-peeling method has been applied to remove them using a methylene chloride solution with acids and it works very well. Small laboratory scale tests have been carried out to develop the commercial process and clarify the mechanism of the swell-peeling method in the present study.When the surface area of UBC is more than 10 cm2, peeling time is independent of the surface area, about 60 seconds, because swelling phenomenon is controlled by the penetration of the liquid through the fine pits on the surface of the paint. This is good for a commercial process. Peeling takes place when the swelling force generated by methylene chloride exceeds the adhesion force between the film and the surface of aluminum, that is weakened by the coexisting acid, especially halogenated acetic acid."

Jan 1, 2000

By F. Qian

Direct impingement of molten metal baths by a gas jet is commonly encountered in such processes as BOF and electric arc furnace steelmaking. Shape and local fluid mechanics in the impinging region is important because it determines the interaction of the metal pool with the surroundings. Goal of the present work is to characterize and understand the interfaces at the impinging region. Using a physical model consisting of water/corn oil and water/kerosene as surrogates for metal/slag, interface shapes for slag-gas, slag-metal and metal-gas are investigated. Influence of transport properties of the two liquids on the shape and flow fields are also experimentally determined under various impinging jet conditions, namely jet momentum and jet height. The viscosity of the slag layer (corn oil or kerosene) has the most significant effect on the interface shape and the induced flow fields. The interface shapes were measured both photographically and by using a surface- tracking resistance probe. The limiting condition at which the jet breaks through the corn oil or kerosene layer and reaches the water layer was determined experimentally

Jan 1, 1994

By Itavahn Alves da Silva, Izabela Diniz Duarte, Carlos Antonio da Silva, Varadarajan Seshadri

Mathematical modeling using computational fluid dynamics has been employed to assess the thermal losses in a steelmaking ladle. Thermal losses lead to thermal stratification and convective flow inside the ladle. The effects of preheating, mineralogical and physical characteristics of the lining as well as thickness of slag cover have been studied and the results obtained from application of the model have been discussed.

Jan 1, 2016

By Lucas Nana Wiredu Damoah, Lifeng Zhang

"Increasing demand for Solar Grade Silicon (SoG-Si) due to rising interest in renewable energy has lead to increased SoG-Si Top – cut scraps generated from the multi-crystalline silicon making process. Due to the high cost of SoG-Si and the potential to use the top-cut scraps as feedstock material, there has been increased effort to develop cost effective and efficient technologies. As a result, several methods to recycle the top-cut scraps are currently been applied, and researched. These include settling under gravitation field, which is a slow process to be industrially applicable. Natural settling of inclusions by gravitational force is a slow process and not attractive to the industry. Recent experiments on Top-cut SoG-Si scrap under high frequency, high voltage, electromagnetic field showed that SiC inclusions settled within a short time to the bottom of the crucible and the characteristic rod-like morphologies of Si3N4 inclusions in SoG-Si were not detected. This study investigates the enhanced settling of SiC inclusions and the behavior of Si3N4 particles under the influence of high frequency, high voltage, electromagnetic field in Top-cut SoG-Si.IntroductionThe photovoltaic industry depends on silicon based PV materials either as single-crystalline silicon, or multi-crystalline Si (MC-Si), or amorphous Si [1] for over 90 % of its market share. [2] MC-Si produced by directional solidification of solar grade silicon melt dominates the silicon PV market. During the directional solidification process, SiC and Si3N4 particles within the melt are pushed by the solidification front to the top of the ingot which is the last to solidify. Therefore the top of the ingot is cut generating what is known as top-cut solar silicon scraps. The Si3N4 particles are mainly from the coating material at the inside surface of the silica crucible and from air absorption during the solidification process. The SiC particles mainly stem from the carbon reduction process of the primary production of silicon [3]. Due to the growth of the PV industry as a result of global demand for clean, reliable, and affordable energy [4], there is the need to develop new methods to compliment exiting ones to recycle SoG-Si waste (e.g. top-cut) for sustainability."

Jan 1, 2012

By Yoji Imai, Akio Watanabe, Masakazu Mukaida

"To clarify the feasibility of alkoxides and acetylacetonates as precursors for laser CVD of metal oxides, vapors of tantalum or titanium alkoxides and zirconium acetylacetonate were irradiated by KrF excimer laser and deposits were characterized by XRD and XPS measurements. As for tantalum and titanium, non-stoichiometric crystalline oxides grew nearly phototropically, however, zirconium oxides deposited showed only halo-pattern by XRD measurements. Electric conductivity measurements of tantalum oxides implied the improvement of the insulating properties by the addition of activated oxygen to the ambient.IntroductionThere has been renewed increasing attention to the metallic oxide thin films because ofits promising usefulness in many applications, such as high-Tc superconductors and ferroelectric devices. A variety of thin film preparation techniques have been studied such as sputtering, chemical liquid deposition (sol-gel and metalorganic decomposition), pulsed laser deposition and chemical vapor deposition (CVD). Among them, we think CVD is the most promising method because it offers a high controllability of morphology and good step coverage at relatively high growth rate. Preparation of oxide films by CVD can be achieved using a precursor containing metallic element and oxygen containing gas such as N20 at the same time. However, metalorganic (MO) compounds which contain both metallic element and oxygen, directly bonded to metallic element, seems to be more favorable because some of MO has a good properties for CVD such as a rather high vapor pressure, stability in ambient and low toxicity."

Jan 1, 1998

By T. H. Courtney, B. R. Murphy

"Nominal room temperature mechanical alloying (MA) has been used to synthesize the high melting temperature NbC and Cu-NbC composites. Elemental powders of Cu and Nb were alloyed in the presence of either graphite or hexane to form nanocrystalline NbC or a Cu-NbC composite. Through control of hot-isostatic-pressing (H/Ping) parameters, we have been able to minimize microstructural coarsening during densijication, and have processed fully dense bulk compacts of both single phase NbC and two-phase Cu-NbC while maintaining a nanocrystalline or near-nanocrystalline structure. These materials generally exhibit high strength and low fracture toughness. However, mechanical properties vary significantly depending upon the Cu content and the method of NbC synthesis (graphite or hexane).INTRODUCTIONMechanical alloying (MA) has been recently used to synthesize a variety of inorganic solids; sulfides (1-2), nitrides (3), borides (4), and carbides (3, 5-8). One advantage of this processing route is that synthesis of fairly high melting temperature materials takes place at what is nominally room temperature. Another advantage is that the structures generated are often nanocrystalline in scale, with attendant interesting properties. The consolidation of these fine structures into near fully dense or fully dense materials while limiting microstructural coarsening is a challenge that has just recently seen limited success (5, 9). We report here on some recent studies of ours dealing with crystallite size and structural analysis of NbC and CuNbC composites consolidated to full density from mechanically alloyed powders. Bulk mechanical properties and their dependence on milling parameters are also presented."

Jan 1, 1994

By Pengcheng Li, Wei-Tong Du, Yu Wang, Gang Wen

Carbon dioxide could be utilized as a weak oxidant and a kind of coolant to oxidize elements, meanwhile, helping control the temperature during the converter vanadium extraction process. However, the optimum content of CO2 and the cooling effect of CO2 at low content have not been reported. In this study, experimental research based on the influence of different CO2 contents from 0% to 25% injected to the vanadium-containing hot metal was carried out, as well as contrast experiments of O2-N2 mixed blowing. The results indicated that the optimum content of CO2 was 15%. Under the optimum condition, the oxidation of [C] was the lowest and the oxidation rate of [V] was 96.9%, while the temperature was also lower than the O2-N2 mixed blowing. This paper provide a potential property for utilizing CO2 during the converter vanadium extraction process.

Jan 1, 2016

By Tabbetha A. Dobbins

We report studies concerning the time frame for catalytic reactions between NaAlH4 (sodium alanate) and TiCl3 during high energy milling. Spectral features in x-ray absorption spectra were analyzed for samples milled for various times (0 minutes, 1 minute, 5 minutes, 25 minutes, and 125 minutes). A structural transition from Ti3+ to Ti0 is observed within the first 5 minutes of milling. The Ti0 structure persists for samples milled for times longer than 5 minutes?even after those samples underwent a subsequent single hydrogen desorption/absorption cycle. Samples milled for less than 5 minutes retain Ti3+. For samples milled for 1 minute, the Ti-K edge position shifts from Ti3+ to Ti0 after a single desorption/absorption cycle. However, the first coordination sphere around the Ti0 absorber occurs at longer distances for 1 minute milled sample. These results hint at the formation of Ti0 pure metallic clusters upon desorption/adsorption cycling of 1 minute milled sample. Previously reported x-ray absorption spectroscopy studies have demonstrated the structural transition from Ti3+ (in TiCl3) to Ti0(determined to be TiAl3 found at the surface of the alanate powder). Aluminum deficiency on the NaAlH4 lattice is responsible for controlling hydrogen absorption capacity. These time-resolved spectroscopy studies suggest the possibility for controlling aluminum deficiency, while still maintaining titanium activation of the alanate powder, by manipulating the coordination environment of the titanium dopant during the first five minutes of high energy milling. Specifically, a possible approach to mitigating aluminum deficiency during doping would be to introduce an alternative species to which the to Ti3+ catalyst would form a metallic bond after the TiCl3 has attached at the surface of the sodium alanate powder and before the Ti3+ forms the TiAl3 intermetallic species.

Jan 1, 2006

By Keith Axler

The high reactivity of plutonium metal presents safety concerns related to material containment during fire scenarios. Plutonium metal is liquid at temperatures achieved under selected fire scenarios. The appearance of liquid plutonium challenges the corrosion resistance of the containment materials. However, by the in situ formation of intermetallic compounds, the plutonium metal can be stabilized as solid and the integrity of the containment vessels preserved. Studies have been conducted to demonstrate candidate materials, including lead, which can be introduced to the liquid-plutonium system and bind the corrosive liquid metal through the formation of intermetallic phases. The results of these investigations will be presented along with a discussion of the experimentally determined phase behavior for the plutonium-lead system.

Jan 1, 1995

By Jeffrey D. Winterton

Keywords: Copper, ion exchange, sulfonic acid, bis-picolylamine, ion exchange modeling, ion exchange kinetics As part of an investigation into the feasibility of using ion exchange resins to recover copper from aqueous waste streams generated during the manufacturing of semiconductor devices, the uptake of copper onto two ion exchange resins was investigated. The resins studied were DOWEX G-26, a standard gel type sulfonic acid resin, and DOWEX M4195, a macroporous chelating resin with a bis-picolylamine functional group. The equilibrium and kinetic behavior of the uptake of copper were investigated over a range of copper concentrations with constant sulfate concentration and different levels of acidity. The homogeneous structure of the G-26 resin yields equilibrium relationships that fit the Langmuir equation, and equilibration times of less than 30 minutes. The uptake behavior of M4195 is complicated by the need to absorb co-ions to maintain electroneutrality, resulting in uptake profiles that change character with increasing copper concentrations, and extended equilibration times.

Jan 1, 2005

By S. Y. Tan

The thermal stability of fully silicided NiSi with arsenic doping on silicon was investigated. The aims of the work were to investigate the Ni silicide phase-related issues associated with arsenic dopant and thermal annealing on Ni-FUSI/HfO2/Si and Ni-FUSI/HfSiO/Si gate stacks. It was found that arsenic-incorporation demonstrated some improvement in both morphology and phase stability of nickel silicided films at high processing temperatures regardless underlying gate dielectrics. The correlations of Ni-Si phase transformation and arsenic doapnt with their electrical and physical changes were established by sheet resistance measurements, X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) analysis. Furthermore, the modulation of the work function (WF) of Ni fully silicided gates by arsenic impurity is presented, comparing the effects of dopant (As) on the WF and silicide phases (NiSi and NiSi2). It confirmed that the work function of NiSi can be tuned by implanting arsenic dopant, but it ineffective for NiSi2 phase.

Jan 1, 2010

By Zhen Zhang, Jiang Diao, Tao Zhang, Yi Ren, Lu Jiang, Xiao-Man Yan, Bing Xie

The precipitation behavior of phosphorus enrichment phase was investigated by slag modification with Al2O3. The mineral phase of the original slag and modified slags were measured by mineral phase microscope, SEM+EDS and XRD. The mechanism of Al2O3 modification was discussed according to the thermodynamic theory analysis software (Factsage version 6.3). The results show that the high phosphorus solid solution (nˊ2CaO·SiO2-3CaO·P2O5) was generated by the continuous reaction of nC2S-C3P (nˊ＜n) solid solution and Al2O3 under 1350℃. The amount of initially precipitated solid solution (nC2S-C3P) was reduced and even disappeared with the increasing of Al2O3. If the addition of Al2O3 is enough in the slag, the high phosphorus solid solution (nˊC2S-C3P) that generated by the above mentioned reaction will continue to react with Al2O3 to produce Ca2Al2SiO7 and even C3P, which was demonstrated that the addition of Al2O3 has a positive influence on the precipitation of phosphorus enrichment phase.

Jan 1, 2015

By Huimin Lu, Lian Zhou, Qiang Li

"A three-dimensional mathematical model is developed for the regenerative rotary hearth furnace with 40 meters medium diameter. The influence of combustion switchover and outlet pressure on the fluctuation and distribution of temperature and pressure is studied with numerical simulation method. The results showed that the temperature field and flow field is suitable for requirement of industrial production; the fluctuation of the temperature field and pressure is acceptable; the influence of outlet pressure on the furnace pressure is great.IntroduceRotary hearth furnace which is originally utilized as heat treating and reheating industrial furnace, now is also used for carbon based DRl production. With the need of market and the concern of resource recycling and environmental issues, the DRl production from ore or from waste material by rotary hearth furnace attracts more and more attentions from steel industry [1,2].When rotary hearth furnace works, the feed pellets are charged on the hearth and rotate within an annular furnace chamber with the process of reduction. For the sake of rapid reduction, usually the depth of the pellet is one or two layers, accounting for less than 90% of the volume of furnace. As result, the exhaust gases carry away a lot of heat, so that energy utilization efficient is low [3]. Currently, in order to reduce the consumption of energy and improve the production efficiency, many methods have been adopted. The regenerative combustion technology is one of the most promising."

Jan 1, 2013

By Yuan She, Qihang Liu, Keng Wu, Hailiang Ren

By observing different coal char’s microstructures and microscopic morphologies during the coking process, the characteristics of COREX coal char’s microstructure and properties were analyzed. MCRI and MCSR were used to respectively describe the reactivity and the strength after reaction of coal char, with those of BF’s coke for reference, and then the physical meaning of MCRI and MCSR were given. MCRI and MCSR were determined by the composition of coal char. For the two kinds of COREX coal, the formula to forecast the hot performance of coal char was set up by making a multiple linear regression between the hot performance and microstructure of the coal char at 1100℃, and the predictive values of coal char’s hot performance at 600℃, 800℃ and 1000℃ coincided well with the measured values.

Jan 1, 2015

By Richard J. Abitz

Thennodynamic geochemical models have been applied to assess the relative effectiveness of a variety of reagents added to aqueous waste streams for the removal of radioactive elements. Two aqueous waste streams were examined: effluent derived from the processing of uranium ore and irradiated uranium fuel rods. Simulations of the treatment train were performed to estimate the mass of reagents needed per kilogram of solution, identify pH regions corresponding to solubility minimums, and predict the identity and quantity of precipitated solids. Results generated by the simulations include figures that chart the chemical evolution of the waste stream as reagents are added and summary tables that list mass balances for all reagents and radioactive elements of concern. Model results were used to set initial reagent levels for the treatment trains, minimizing the number of bench-scale tests required to bring the treatment train up to full-scale operation. Additionally, presentation of modeling results at public meetings helps to establish good faith between the federal government, industry, concerned citizens, and media groups.

Jan 1, 1996

By Hani Henein

Recent innovations in atomization of molten metals have occurred in the area of single fluid atomization. Impulse Atomization (IA), one of the single fluid techniques, provides unique capabilities to study different regimes of atomization in a controlled environment. By changing processing variables, a mono-dispersed distribution of droplets above one millimeter in diameter can be produced. This is accomplished through proper characterization of the forces influencing the process and in particular the flow of melt through the orifice. This paper will discuss the approach and illustrate results with molten aluminum and cobalt.

Jan 1, 2006

By R. Y. Wan, S. L. Chryssoulis

"Gold associations were established in a·biooxidized, chlorinated CIL residue assaying 0.02 oz Ault and in a biooxidized thiosulfate leach residue assaying 0.01 oz Au/t. A detailed mineralogical study involved: assays of screened fractions; light microscopy; ion probe microanalysis to quantify 'invisible' gold in sulfide minerals; proton probe microanalysis to detect and quantify preg-robbed gold. In the CIL residue, most of the gold is preg-robbed (71 %). In the thiosulfate leach residue, gold occurs mainly as submicroscopic disseminations in microcrystalline quartz (chert). In both residues, the 'invisible' gold in pyrite accounts for a minor fraction of the gold assay. Quantitative determination of the gold occurrence in the two residue samples established conclusively that gold adsorption on carbonaceous matter in the thiosulfate leach is of minor importance.Acknowledgement: published with permission of Newmont Gold Company."

Jan 1, 1997

By Ragnhild Aune

In fire refining of copper, the affinities of various impurity elements on dissolved oxygen is of great significance. Further, in the design of oxygen probes in liquid copper, the influence of solute interactions on the activity of oxygen need to be considered in order to evaluate the oxygen concentration in molten copper. The present paper presents a series of measurements of the activities of oxygen in liquid Cu-M-o alloys (where M stands for Mn, Zn, As, Se or Te) carned out by the present group employing the solid electrolyte galvanic cell technique. Extreme care was taken to control the oxygen potentials in the inert gas atmosphere, and to keep the oxygen levels very low in the molten metal. The oxygen content was determined by analysis of the samples taken out from the melt. The results obtained showed that Mn has a strong negative influence on the activity coefficient of oxygen in liquid copper. A similar, but less prominent effect was observed in the case of Zn. Arsenic had no influence on the activity of oxygen in Cu (liq.). Se and Te had slight negative effect on oxygen activities in copper at XQ >10-5, while at lower oxygen levels the interaction coefficients were found to be positive. The results obtained were compared with empirical models for the calculation of interaction coefficients available in literature.

Jan 1, 2003

By A. Onozaki

The Iijima Refinery was put into operation in 1972 and today has an annual production capacity of 156,000 tons of SHG electrolytic zinc. At the Iijima Refinery, the recoveries of gold and silver are 98.0% and 98.2%, respectively. Gold contained originally in the zinc concentrates reports in the Cu-Pb-Ag residue produced in the residue treatment process. Silver contained in the concentrates is distributed between the Cu-Pb~Ag residue and the copper cake produced in the purification process. The Cu-Pb-Ag residue, which contains gold and silver, is sent to the Oyachi flotatfon plant of the Kosaka Smelter; about 82% of the gold and about 85% of the silver are recovered in the copper flotation concentrate.. In this paper, the distribution of gold and silver in the Iijima. Refinery is discussed and operational results of the Oyachi flotation plant are presented.

Jan 1, 1990