Materials Processing Fundamentals: Molten & Gas State Processing
Sponsored by: TMS Extraction and Processing Division, TMS: Process Technology and Modeling Committee
Program Organizers: Antoine Allanore, Massachusetts Institute of Technology; Jonghyun Lee, Iowa State University; Guillaume Lambotte, Boston Electromet

Thursday 2:00 PM
March 2, 2017
Room: 17B
Location: San Diego Convention Ctr

Session Chair: Samuel Wagstaff, Novelis; Jonghyun Lee, Iowa State University

2:00 PM  
Thermal Analyses of Silver-based Sulfosalts in Air: Fiseha Tesfaye1; Daniel Lindberg1; 1Åbo Akademi University
    The roasting of sulfide ores and concentrates is an important process step in the production of valuable metals and chemicals. It involves gas–solid reactions to remove volatile components from the sulfide ores and concentrates. Silver-based sulfosalts are common minerals in precious and base metal sulfide ores. In this work, the sulfosalts in the Ag-(Cu,Bi)-S systems have been studied under oxidizing conditions. The sulfosalts were synthesized from the pure simple sulfides in an evacuated quartz ampoule. Then, the synthesized samples were thermally analyzed in the temperature range from 298 to 1173 K by the simultaneous a simultaneous DTA-TGA analyzer. Based on the calorimetric measurements, the maximum thermal stabilities of the phases in oxidizing conditions are determined. Different steps of the gas-solid reactions within the pyrometallurgical roasting temperature range are described, and the obtained results are compared with the estimated and literature values.

2:20 PM  
Influence of Oxygen on Surface Tension of Zr: Jonghyun Lee1; Jie Zhao1; Michael SanSoucie2; Rainer Wunderlich3; Jan Rogers2; Hans Fecht3; Robert Hyers1; 1University of Massachusetts; 2NASA Marshall Space Flight Center; 3Ulm University
    Thermophysical properties of Zr and Zr-O are being measured using the Materials Science Laboratory – Electromagnetic Levitator (MSL-EML) in the International Space Station in order to study the influence of oxygen on surface tension and viscosity. As part of ground support activities, thermophysical properties of various compositions of Zr-O system were measured using the Electrostatic Levitator at NASA Marshall Space Flight Center in Huntsville, AL. Zr-O samples with several difference oxygen concentrations were tested and the oxygen influence on the thermophysical properties were investigated. The results of this study will provide the reference data for the space experiments.

2:40 PM  
Oscillation of a Zirconium Droplet – Experiments and Numerical Simulations: Jonghyun Lee1; Kaushal Sumaria1; Robert Hyers1; 1University of Massachusetts
    Oscillation of a droplet was predicted using the Volume of Fluids method. A 2-D axi-symmetric single phase droplet model was built in a commercial computational fluid mechanics software, ANSYS Fluent. With an initial deformation of 3% ellipticity, the model was allowed to dampen freely. The change in cross-sectional area was extracted to determine the oscillation frequency and viscosity. The numerical results were compared with the experiments with molten zirconium and they showed good agreement.

3:00 PM  
Gallium Evaporation Behavior for Purification in Molecular Beam Epitaxy (MBE): Kyungjean Min1; David Johnson1; Kevin Trumble1; 1Purdue University
    The electron mobility in GaAs/AlGaAs heterostructures has been shown to correlate with the purity of the Ga source material in the Molecular Beam Epitaxy (MBE). Distillation of Ga was performed in the MBE to reduce impurities before growing AlGaAs/GaAs heterostructures at Purdue University and higher electron mobility was achieved after distillation compared to the initial 7N (99.99999%) Ga. During distillation and growth, 25% of the initial Ga was spent and the impurity concentration of Ge in the residual Ga was measured by ICP-MS to decrease from 690 ppb to 65 ppb. The evaporated amounts of Ga and impurities are analyzed by the Langmuir-Knudsen equation, as well as active oxidation of Ge. Geometric effects of evaporation from the crucible are analyzed using Clausing’s theory for the flux of angular distribution in evaporation from an area source in a cylindrical crucible.

3:20 PM Break

3:40 PM  
Investigation of Mixing Process in a Steel Ladle with Top Stirring Lance Using CFD: Guangwu Tang1; Armin Silaen1; Hoyong Hwang2; Megan Pratt3; Russell Mulligan2; Chenn Zhou1; 1Purdue University Northwest; 2ArcelorMittal; 3Toyota Motor Manufacturing Indiana
    Gas stirring treatment in steel ladle is an important step to ensure good steel product quality. The mixing efficiency of the gas stirring in steel ladle is affected by various factors. In order to improve the mixing efficiency in a steel ladle, a computational fluid dynamics (CFD) model has been developed based on an industrial top gas stirring ladle. By using the model, detailed flow pattern is studied and the mixing time is calculated. The model has been validated with industrial experiment on different operating conditions. The examination of mixing time in ladle under various operating conditions shown that the turbulence intensity due to the gas stirring plays an important role in the mixing process. The results also show that adjusting the lance position by moving the lance away from the ladle center has great effect on reducing mixing time.

4:00 PM  
Mass Transfer of Al and Ca between Silicon and Synthetic SiO2-CaO-Al2O3 Slags: Erlend Bjørnstad1; Gabriella Tranell1; 1NTNU
    The mass transfer of Al and Ca between silicon and synthetic SiO2-CaO-Al2O3slags of varying composition has been investigated, using different experimental set-ups. Samples were kept at 1600 C, varying the holding times in an individual crucible kinetic series set-up or sampled at given sample intervals in a larger crucible set-up. Solute concentrations of Al and Ca in Si and slags were found by ICP-MS and XRF. This work compares these results to observations from industrial Si refining measurement campaigns. A model for interpreting kinetic mass transfer phenomena observed for parallel Al and Ca mass transfer between slag and Si, is also discussed.