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Development of a Novel Non-Consumable Anode for Electrowinning Primary Aluminum

Description: The principal goal of the project was to determine through theoretical considerations and from chemical and electrochemical laboratory studies the technical and economic feasibility for the substitution and retrofitting of an SOFC-type anode for today's carbon anode in a cell for electrowinning primary Al. However, solubility measurements showed that no value of cryolite ratio can exist where the solubilities of the solid electrolyte components (zirconia and especially yttria) would be small relative to the alumina solubility. Therefore, the utilization of the proposed SOFC-type anode cannot be realized for any cell involving a cryolite-base solvent. However, the project suggested that the SOFC-type anode scheme might be successful if the solvent/electrolyte for electrowinning Al could be changed to a fused sulfate melt. During the solubility experiments, electrochemical probes were developed, and a bath characterization was defined, to measure quantitatively the acid-base character of cryolite melts. The measured acid-base behavior was then used to correlate the alumina solubility in cryolite over a wide range of cryolite ratio at 1300K. A mathematical modeling of the alumina solubility as a function of basicity identified three solutes of Al{sub 2}O{sub 3} in cryolite-base melts: Na{sub 2}Al{sub 2}OF{sub 6}, Na{sub 2}Al{sub 2}O{sub 2}F{sub 4}, and Na{sub 4}Al{sub 2}O{sub 2}F{sub 6} as acidic, neutral and basic solutes, respectively. For the first time, the stereochemistry (geometries) of these complex solutes was clarified. For the non-oxygen containing Al-F complex anions, Na{sub 3}AlF{sub 6} and NaAlF{sub 4} were also considered as solutes, and some NaF (but no AlF{sub 3}) could remain in the melts. The previously suggested solute Na{sub 2}AlF{sub 5} was found to be unstable. The strong complexing in the cryolite/alumina system means that the bath is highly buffered so that a significant shift in basicity is not possible and therefore the alumina solubility does not vary greatly. The maximum ...
Date: December 4, 2003
Creator: Rapp, Robert A. & Zhang, Y.
Partner: UNT Libraries Government Documents Department


Description: Assessment of soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS) is important for preserving environmental quality and increasing agronomic yields. The mechanism of physical SOC sequestration is achieved by encapsulation of SOM in spaces within macro and microaggregates. The experimental sites, owned and maintained by American Electrical Power, were characterized by distinct age chronosequences of reclaimed minesoils and were located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites were reclaimed both with and without topsoil application, and were under continuous grass or forest cover. In this report results are presented from the sites reclaimed in 2003 (R03-G), in 1973 (R73-F), in 1969 (R69-G), in 1962 (R62-G and R62-F) and in 1957 (R57-F). Three sites are under continuous grass cover and the three under forest cover since reclamation. Three bulk soil samples were collected from each site from three landscape positions (upper; middle, and lower) for 0-15 and 15-30 cm depths. The samples were air dried and using wet sieving technique were fractionated into macro (> 2mm), meso (2-0.25 mm) and microaggregate (0.25-0.053 mm). These fractions were weighted separately and water stable aggregation (WSA) and geometric mean (GMD) and mean weight (MWD) diameters of aggregates were obtained. The soil C and N concentrations were also determined on these aggregate fractions. Analysis of mean values showed that in general, WSA and MWD of aggregates increased with increasing duration since reclamation or age of reclaimed soil for all three landscape positions and two depths in sites under continuous grass. The forest sites were relatively older than grass sites and therefore WSA or MWD of aggregates did not show any increases with age since reclamation. The lower WSA in R57-F site than R73-F clearly showed the effect of soil erosion on aggregate stability. Higher aggregation and aggregate diameters in ...
Date: April 1, 2005
Creator: Shukla, M.K. & Lal, R.
Partner: UNT Libraries Government Documents Department

Summer Workshop: Molecular Basis, Physiology and Diversity of Microbial Adaptation

Description: This summer workshop successfully exposed beginning graduate students, research technicians from industry, and other scientists to modern concepts and experimental protocols in an area that both DOE and NSF perceived to be lacking in U.S. science. 70 students participated in this workshop over 5 summers. Each summer, 12-16 students spent 2-4 weeks at The Ohio State University covering four distinct modules through lectures, laboratory sessions, and interaction with internationally recognized eminent scientists.
Date: May 7, 2002
Creator: Tabita, F. R.
Partner: UNT Libraries Government Documents Department

Modeling the Mechanical Performance of Die Casting Dies

Description: The following report covers work performed at Ohio State on modeling the mechanical performance of dies. The focus of the project was development and particularly verification of finite element techniques used to model and predict displacements and stresses in die casting dies. The work entails a major case study performed with and industrial partner on a production die and laboratory experiments performed at Ohio State.
Date: February 27, 2004
Creator: Miller, R. Allen
Partner: UNT Libraries Government Documents Department

Contaminant Organic Complexes: Their Structure and Energetics in Surface Decontamination

Description: The Department of Energy has a goal of decontaminating an estimated 180,000 metric tons of metal wastes in various surplus facilities. Uranium (U) and other radioactive actinides and lanthanides are embedded within the mixed oxide structures of the passivity layers of corroded iron and steel. These toxic metals can be dissolved out of the surface layers by a naturally occurring bacterial siderophore called Desferrioxamine B (DFB). DFB is a trihydroxamate ligand with one amine and three hydroxamate groups, which chelates with metals through hydroxamate coordination. Complexation of DFB with U can be utilized in decontamination strategy of the passivity layers. Therefore, we have been studying reactions of uranyl U(VI) with zerovalent iron (Fe0) followed by dissolution by DFB. The objectives were to determine the structure and speciation of solution and solid phases of U and to assess the effectiveness of DVB in U dissolution.
Date: July 12, 2005
Creator: Traina, Samuel & Sharma, Shankar
Partner: UNT Libraries Government Documents Department

Die Casting Part Distortion: Prediction and Attenuation

Description: The goal of this research was to predict the part deformation and residual stresses after ejection from the die and cooling to room temperature. A finite element model was built to achieve this goal and several modeling techniques were investigated throughout this research. Die-casting is a very complex process and the researchers are faced with a large number of hard to solve physical problems when modeling the process. Several assumptions are made in our simulation model. The first significant assumption is the instantaneous cavity filling. This means that the cavity filling stage is not considered in our model. Considering the cavity filling stage increases the modeling complexity as a result of different flow patterns. expected in the shot sleeve, gate, runner and different cavity features. The flow of gas from the cavity through the vents is another problem that is ignored in our model as a result of this assumption. Our second assumption is that the cast metal has uniform temperature distribution inside the cavity, at the starting point of simulation. This temperature is assumed to be over liquidus limit, i.e. the solid fraction is 0.0% of the cast metal. The third assumption is due to ABAQUS (commercial software used in this research) limitations. ABAQUS cannot deal with multi-phase models; therefore we use solid elements to define the casting instead of multi-phase (liquid/solid) elements. Liquid elements can carry the hydrostatic pressure from the shot sleeve and apply it on the cavity surfaces, while the solid elements do not have this capability. To compensate for this assumption we add the cavity pressure as a boundary condition and apply it on the cavity surface separately from the part. Another issue with this assumption is that, liquid casting can follow the cavity shape when it distorts. With the use of solid elements to ...
Date: February 12, 2002
Creator: Dr, R. Allen Miller
Partner: UNT Libraries Government Documents Department

Development of a Probabilistic Technique for On-line Parameter and State Estimation in Non-linear Dynamic Systems

Description: The DSD (Dynamic System Doctor) is a system-independent, interactive software under development for on-line state/parameter estimation in dynamic systems (1), partially supported through a Nuclear Engineering Education (NEER) grant during 1998-2001. This paper summarizes the recent accomplishments in improving the user-friendliness and computational capability of DSD
Date: April 1, 2002
Creator: Aldemir, Tunc; Miller, Don W.; Hajek, Brian k. & Wang, Peng
Partner: UNT Libraries Government Documents Department

Local Measurement of Fuel Energy Deposition and Heat Transfer Environment During Fuel Lifetime Using Controlled Calorimetry

Description: A comprehensive description of the accomplishments of the DOE grant titled, ''Local Measurement of Fuel Energy Deposition and Heat Transfer Environment During Fuel Lifetime using Controlled Calorimetry''.
Date: December 31, 2001
Creator: Miller, Don W.; Kauffmann, Andrew; Kreidler, Eric; Li, Dongxu; Liu, Hanying; Mills, Daniel et al.
Partner: UNT Libraries Government Documents Department

Final Report of Strongly Interacting Fermion Systems

Description: There has been significant progress in three broad areas: (A) Optical properties, (B) Large-scale computations, and (C) Many-body systems. In this summary the emphasis is primarily on those papers that point to the research plans. At the same time, some important analytic work is not neglected, some of it even appearing in the description of large-scale Computations. Indeed one of the aims of such computations is to give new insights which lead to development of models capable of simple analytic or nearly analytic analysis.
Date: June 25, 2001
Creator: Wilkins, J. W.
Partner: UNT Libraries Government Documents Department