Applications of Process Engineering Principles in Materials Processing, Energy and Environmental Technologies: An EPD Symposium in Honor of Professor Ramana G. Reddy: Thermodynamics and Kinetics
Sponsored by: TMS Extraction and Processing Division, TMS Light Metals Division, TMS: Energy Committee, TMS: Hydrometallurgy and Electrometallurgy Committee
Program Organizers: Shijie Wang, Rio Tinto Kennecott Utah Copper; Michael Free, University of Utah; Shafiq Alam, University of Saskatchewan; Mingming Zhang, Arcelor Mittal; Patrick Taylor, Colorado School of Mines

Thursday 2:00 PM
March 2, 2017
Room: 16A
Location: San Diego Convention Ctr

Session Chair: Michael Free, University of Utah

2:00 PM  
Vaporization Thermodynamics of Mg, K, and Rb Using Knudsen Torsion Effusion Thermogravimetry Method: L.-N. N. Nforbi1; Anjali Talekar1; Dhanesh Chandra1; Wen-Ming Chien1; Kai Lau2; Hans Hagemann3; Yaroslav Filinchuk4; J-C Zhao5; 1Uni. of Nevada, Reno; 2SRI International (Retired); 3Uni. of Geneva; 4Uni. of Louvain (Belgium); 5Other
    The vapor pressure and molecular weight of effusing vapors of Mg(BH4)2 (KBH4) and RbBH4 were determined by torsion-effusion gravimetric method. The Mg(BH4)2(s) → Mg(s) + 2B(s) + 4H2(g) to predominantly H2 gas (~ 95 %) with a small amount of Mg(BH4)2 (~ 5%) in the gas phase. The equations for vapor pressures for crystalline Mg(BH4)2 are given by: logPTotal (bar) = 9.2303 - 7286.2/T, logPEq. MgBH4)2(bar) = 8.2515 - 7286.2/T, and logPEq.H2(bar) = 9.1821 - 7286.2/T. The solid KBH4 disproportionated to B(s), K(g) and H2(g) during vaporization; is log PEq.(KBH4) (bar) = (8.134 0.041) – (9557.7 28.7)/T. Likewise the RbBH4 also disproportionated equilibrium decomposition pressure Peq equation is log PEq(RbBH4) (bar) = (10.053 0.037) – (9591.4 24.0)/T. The vaporization pressures, disproportionation of each of these borohydrides, partial pressures of disproptionated gases, Gibbs energy changes (ΔG) and standard enthalpies of reaction for decomposition will be presented.

2:20 PM  
Thermodynamic Studies on the Mg-B System using Solid State Electrochemical Cells: Muhammad Imam1; Ramana Reddy1; 1The University of Alabama
    This study provides a reasonable evaluation of the Mg-B binary system. Magnesium and Boron (Mg-B) alloys were investigated to determine their thermodynamic properties employing solid state electrochemical cells based on CaF2 electrolyte represented as (-)Pt,Ar/{Mg+CaMgF4 } ||CaF2 || {[Mg-B](alloy ) +CaMgF4 }/Ar,Pt(+). Investigations were performed over the temperature range of 773 to 873K to measure the electromotive force (EMF), which was used to derive the partial Gibbs Free energies of the alloys in the composition range of XB=0.07 to 0.95. The activities of Mg were also calculated from partial Gibbs Free energies. The activities of Mg in MgB2, MgB4, and MgB7 were expressed as a function of temperature respectively, ln aMg= 4.27-9.32103/T, ln aMg = -7.54+6.67103/T, and ln aMg= 4.93-19.57103/T, where T is the temperature in K. From this expression, the activity of Mg for these intermediate phases can be extrapolated at a higher temperature to get the accurate phase boundaries for the Mg-B system.

2:40 PM  
Reduction Behavior of MnO and SiO2 from SiMn Slags: Trine Larssen1; Merete Tangstad1; 1Norwegian University of Science and Technology
    The reduction behavior and kinetics of MnO and SiO2 from different SiMn slags were experimentally investigated in CO atmospheric pressure between 1500 and 1650 C. A TGA-type furnace was used to measure the mass loss during the reduction of MnO and SiO2. Low reduction was obtained in charges based on manganese ore, quartz and coke (and limestone). A slightly lower reduction was observed when limestone was added to the charge. The impact of trace elements were evident when small amounts of sulphur was added to the systems. Due to the scarce kinetic information on SiMn slag reduction, activation energies of MnO and SiO2 were also investigated.

3:00 PM  
Empirical Activation Energies of MnO and SiO2 Reduction In SiMn Slags between 1500 and 1650C: Pyunghwa Kim1; Ryosuke Kawamoto2; Trine Larssen1; Merete Tangstad1; 1Norwegian University of Science and Technology; 2The University of Tokyo
    The reduction rates of MnO and SiO2 were investigated for various charge compositions. The empirical activation energies of MnO and SiO2 reduction from SiMn slags were calculated between 1500 to 1650 C under CO atmospheric pressure. The amount of metal produced at different temperatures were compared, and the Arrhenius plots were described for each slag A, slag B and synthetic slag, which shows that the raw material have significant influence on the reduction rate. The rate of Mn-produced in slag A was faster than slag B despite of the relatively lower driving force. The lower rate constant in slag B implies that other kinetic factors, such as viscosity, affects the reduction rate. The estimated activation energies of MnO were 920, 304 and 975 kJ/mol MnO for slag A, slag B and synthetic slag, respectively. The rates of Si-produced were similar and slow for all slag types. However, the different activation energies of SiO2 between industrial ores and synthetic materials implied that the trace elements can have catalytic effects toward SiO2 reduction in SiMn slags. The estimated activation energies of SiO2 reduction were around 800 kJ/mol for slag A and slag B.

3:20 PM Break

3:40 PM  
Experimental Evaluation of Thermodynamic Interactions between Tellurium and Various Elements in Molten Iron: Shun Ueda1; Yuichi Matsuki1; Kazuki Morita1; 1The University of Tokyo
    Tellurium has mainly been used as an alloying element for resulfurized free-machining steel. It globularizes MnS inclusions and improves both machinability and mechanical properties of the steel. This effect is quite sensitive to tellurium concentration. Therefore, it should be controlled accurately during the secondary refining process, based on the thermodynamic properties of tellurium in molten iron. In the present study, Wagner's interaction parameters of various elements on tellurium were experimentally evaluated by the vapor-liquid equilibration, where the vapor pressure of tellurium was controlled using the transpiration method. The obtained values are compared with those of oxygen and sulfur, and they were found to correlate with Gibbs energy for the formation of corresponding oxides, sulfides, and tellurides. Furthermore, these relations could provide unreported interaction parameters from those available.

4:00 PM  
Thermodynamics of Simultaneous Desulfurization and Dephosphorizaion of SiMn Alloy: Jong-Min Jeong1; Jaehong Shin1; Chul-Woo Nam2; Kyung-Ho Park2; Joohyun Park1; 1Hanyang University; 2Korea Institute of Geoscience and Mineral Resources (KIGAM)
    Because sulfur and phosphorus are very harmful in steel industries, there are increasing requirements for refining these elements from ferroalloys industries. Hence, in the present study, simultaneous desulfurization (de-S) and reducing dephosphorization (Rde-P) from silicomenganese (SiMn) alloy were investigated using metal-slag equilibration method under highly reducing condition at 1500oC. Experiments were carries out by equilibrating SiMn alloy and MnO-based slag in graphite crucible under p(O2)=10-18 atm. Slag composition was designed by changing basicity (CaO/SiO2) and MnO content with fixed Al2O3 (=20%) and MgO (=5%). Sulfur and phosphorus distribution ratio between metal and slag was exhibited as a function of basicity. De-S ratio increased with increasing basicity until C/S=1.5, whereas De-P ratio was not significantly affected by slag basicity. This is because the thermodynamic driving force of de-S reaction is greater than that of Rde-P reaction under present experimental conditions. De-S and Rde-P ratios commonly increased with decreasing oxygen partial pressure.

4:20 PM  Cancelled
Isothermal Reduction Behavior of CaO-Fe2O3-8wt%SiO2 System at 1123K, 1173K and 1223K with CO–N2 Gas Mixtures: Chengyi Ding1; Xuewei Lv1; Kai Tang1; Senwei Xuan1; Yun Chen1; Jie Qiu1; 1Chongqing University
    SiO2 is a significant chemical component in the formation of SiO2–Fe2O3–CaO–Al2O3 from CaOFe2O3 (CF). The influence of SiO2 on the reducibility of the CaO–Fe2O3–SiO2 system was fully examined in this study. The isothermal reduction kinetics of CF and CF8S were investigated through thermogravimetric analysis at 1123, 1173, and 1223 K with 30% CO and 70% N2 gas mixtures. The reduction of the samples with 8% SiO2 was not only highly accelerated but also proceeded easily. Rate analysis revealed that CF and CF8S reduction occurs in two stages, the Fe3O4-to-FeO stage overlaps with the previous Fe2O3-to-Fe3O4 stage and tends to approach the following FeO-to-Fe stage with the addition of SiO2. The apparent activation energy values of CF and CF8S reduction are 46.89 and 8.71 kJ·mol−1. Sharp analysis indicated that CF and CF8S reduction was expressed by the Avrami–Erofeev equation presenting a 2D shrinking layer reaction.

4:40 PM  
A Review of Some Studies on Impurity Capacity Predictions in Molten Melts: Bora Derin1; 1Istanbul Technical University
    This study is a collection of both newly published and/or presented works on Impurity Capacity Predictions in Molten Melts which were carried out by our research group. Sulfide, phosphate, Phosphide, Nitride and Carbide Capacity Predictions in binary, ternary and multicomponent melts were calculated by Reddy-Blander Model and an Artificial Neural Network Approach.