Materials Processing Fundamentals: Thermodynamics on Metals and Slags Processing
Sponsored by: TMS Extraction and Processing Division, TMS Materials Processing and Manufacturing Division, TMS: Process Technology and Modeling Committee
Program Organizers: Jonghyun Lee, Iowa State University; Samuel Wagstaff, Oculatus Consulting; Alexandra Anderson, Gopher Resource; Fiseha Tesfaye, Metso Metals Oy, Åbo Akademi University; Guillaume Lambotte, Boston Metal; Antoine Allanore, Massachusetts Institute of Technology

Wednesday 8:30 AM
March 17, 2021
Room: RM 42
Location: TMS2021 Virtual

Session Chair: Guillaume Lambotte, Boston Metal; Fiseha Tesfaye, Åbo Akademi University


8:30 AM  
Effect of Slag Conductivity on Decarburisation Reaction Kinetics: Jayasree Biswas1; Kenneth Coley2; 1McMaster University; 2Western University
    In basic oxygen steelmaking, metal droplet decarburization plays an important role in overall refining efficiency due to the bloating phenomena. In this work, a fundamental study of decarburization reaction kinetics for liquid metal droplets in oxidizing slag have been conducted. This study proposes a kinetic model which includes the effect of slag conductivity on decarburization reaction kinetics. It is proposed that during the decarburization process a charge build-up at the slag metal interface introduces an electric field which opposes the movement of oxygen ions towards slag-metal interface. This effect is believed to be the cause of the sudden shutdown of the decarburization process for metal droplets observed for low conductivity slags, in contrast to the case of high conductivity stage where decarburization was observed to continue to equilibrium.

8:50 AM  
Experimental Characterization of Liquid Metal Bubble-driven Flows Modeling the Situation in a Steel Ladle : Thomas Wondrak1; Christian Bruch2; Sven Eckert1; Pascal Gardin3; Gernot Hackl4; Helmut Lachmund5; Hans-Bodo Lüngen6; Hans-Jürgen Odenthal7; Klaus Timmel1; Bernd Willers1; 1Helmholtz-Zentrum Dresden-Rossendorf; 2Saarstahl AG; 3ArcelorMittal; 4RHI-Magnesita; 5Dillinger Hüttenwerke; 6Steel Institute VDEh; 7SMS group GmbH
    In metallurgy, gas-liquid two-phase flows are relevant for mixing, degassing and refinement. The reliable prediction of the hydrodynamic performance in gas-stirred ladles is of utmost relevance for optimization and process control. A new experimental facility has been designed and constructed for systematic investigations of gas bubbles rising inside the alloy SnBi, its thermophysical properties are very similar to those of steel. Low operating temperatures (T~200°C) allow the use of powerful measuring techniques. The cylindrical fluid vessel represents a 1:5.25 model of an industrial 185 t ladle and is equipped with a vacuum pump to achieve low-pressure conditions for VOD (Vacuum Oxygen Decarburization) applications as well. The experiments provide a copious data base about the flow regimes, void fraction, liquid and bubble velocities, and bubble properties, which can be used to provide so far unknown boundary conditions for CFD simulations of various metallurgical reactors such as steelmaking converters or steelmaking ladles.

9:10 AM  
Influence of Slab Transportation and Handling Practice on Crack Sensitivity of Micro-alloyed Steels: Hossam Shafy1; Heinz Palkowski1; 1Clausthal University of Technology
    Different steel grades are subjected to surface cracking on the route from continuous casting to hot rolling. One of the causes is the local formation of hard structures and/or fine precipitates after casting depending on the slab handling and position in a pile, which is believed to influence its cracking risk. To evaluate the influence of the slab position on the cooling rate, a FEM model was built to calculate different cooling profiles in short and high piles using Abaqus CAE. The effect of different transport routes on phase transformations and sizes of precipitates for two steel grades (A: 0.08% C, 0.12% Ti and 0.05% Nb; B: 0.08% C and 0.001% Ti) were investigated using TM simulator DIL805A, mechanical testing, MatCalc software and means of LOM and SEM analysis. Critical conditions leading to bainitic structure and fine precipitates instead of a homogenous ferrite/pearlite matrix and larger precipitates could be defined.

9:30 AM  
Low Temperature Aluminothermic Reduction of Metal Oxides: Jawad Haidar1; 1Kinaltek Pty Ltd.
    Aluminothermic reduction of metal oxides commonly known as the thermite process has remained unchanged since its inception in 1893. This reduction process is highly exothermic and has an activation temperature above the melting point of Al at around 660⁰C, with the reactants reaching up to 2000⁰C. We present a variant of the thermite process capable of reducing metal oxides at low temperatures in the range 50⁰C to 600⁰C. Results will be presented for reduction of ZnO, CuO, SnO2, Sb2O5, Fe2O3, NiO, V2O3, Ta2O5 and WO3 with yields up to more than 99%. For most of those oxides, the by-products can be separated from the metal powder products by washing in water. This novel reaction route enables a new simple pathway for reducing metal oxides through solid-solid reactions, directly leading to metal and metal alloy powders and allowing to conserve morphological features from the starting precursors.

9:50 AM  
Modelling of Metal Loss in Ferromanganese Furnace Tapping Operations: Quinn Reynolds1; Jan Erik Olsen2; 1Mintek; 2SINTEF Industry
    During the pyrometallurgical production of industrial alloys such as ferromanganese in electric smelting furnaces, molten slag and metal phases are tapped from the unit at regular intervals. This involves opening a dedicated channel in the furnace sidewall (the tap-hole) and allowing the contents of the vessel to drain through it. After exiting the tap-hole, the stream of molten material is directed along open launders and empties into one or more storage ladles. Intermixing of slag and metal phases occurs frequently during the latter stages of the tapping process, and if not carefully managed, can result in significant metal being lost to the waste slag by entrainment. This paper presents the results of a computational fluid dynamics study of the multiphase free surface fluid flow in tapping launders and ladles, with a specific focus on the impact of various design and operational parameters on metal losses to the slag.

10:10 AM  
Carbothermal Reduction of Brazilian Linz Donawitz-LD Steel Sludges: Mery Gomez Marroquin1; Jose Carlos D´Abreu2; Enrique Dionisio-Calderón2; Nilton Cárdenas-Falcón3; Abraham Terrones - Ramirez4; Jhony Huarcaya-Nina5; Kim Phatti - Satto4; Fernando Huaman-Perez6; 1APMMM/Universidad Nacional de Ingeniería; 2Pontifícia Universidade Católica do Rio de Janeiro ; 3Pontificia Universidad Católica del Perú ; 4FIGMM Universidad Nacional de Ingeniería; 5FIA Universidad Nacional de Ingeniería; 6FIQT Universidad Nacional de Ingeniería
    Carbothermic reduction was conducted using coarse (Sample A) and fine (Sample B) Brazilian Linz Donawitz-LD steel sludges and a sample of Peruvian anthracitic metallurgical coke (AMC) at 82.5% of fixed carbon. Specimens of 1g of sample A and sample B preliminarily mixed with AMC at Fe/C:1/2 were weighted. Sample A / AMC and Sample B / AMC, reduction time and reduction temperature were identified as factors or independent variables. Conversions (α) or % Reduction were selected as dependent variables. The values of weight ratios for Sample A / AMC and Sample B / AMC (3/7 and 7/3, respectively), reduction temperatures of 600 and 900°C and reduction times lapses of 30 and 60 minutes, corresponding to their minimum as well as their maximum level of fluctuation respectively, were carry out via two design of experiments based in the factorial method 23; one for each sample (A and B); using a Brazilian statistics software called COLMEIA - Snedecor algorithm F in order to evaluate the effects simple, double and multiple of factors over the conversions (α) or % Reduction. Carbothermic reduction tests were performed at the optimal weight ratio (sample A /AMC: 3/7 and sample B /AMC: 3/7), reduction temperatures: 600, 700, 800 and 900° C and reduction times: 20, 30, 40, 50 and 60 minutes in order to estimate k- specific reaction rate constant, Ea-apparent activation energy and the A-Arrhenius pre-exponential frequency factor. The kinetic models that better fitted to the conversions (α) of both samples (A and B) were: Boundary Chemical Reaction Model for spherical symmetry (BCRM-ss): 1-(1-α)^(1⁄3)=kt and the model of simple exponential continuous reaction (MSECR): -ln(1-α)=kt. The kinetic parameters obtained were: (1) Sample A: Ea = 7. 45 - 8.08 kJ / mol and A = 0.009 - 0.032 Hz for a linear correlation between 0.8241 and 0.8276 and (2) Sample B: Ea = 19.36 - 21.94 kJ / mol and A = 0.05 - 0.21 Hz for a linear correlation between 0.9758 and 0.9777.

10:30 AM  
Liquid-liquid Extraction Thermodynamic Parameter Estimator (LLEPE) for Multicomponent Separation Systems: Titus Quah1; Chukwunwike Iloeje1; 1Argonne National Laboratory
    Gibbs Energy Minimization is a powerful tool for modeling liquid-liquid extraction (LLE) in multicomponent systems, but requires key thermodynamic parameters that are often unavailable for several applications involving critical and rare earth material separations. Our earlier work demonstrated an approach for estimating these properties via regression to equilibrium isotherm data, but identified limitations regarding applicability to higher concentration systems, sensitivity to experimental data, and ease of implementation. To extend the accessibility and applicability of Gibbs Energy Minimization for modeling LLE, this study presents LLEPE, an open-source Python package for estimating thermodynamic parameters. LLEPE extends parameter estimation to include aqueous-phase Pitzer coefficients that capture the effects of ionic interactions, and offers analysis and visualization tools that assess experimental data quality and prediction model performance. The study discusses LLEPE’s approach, and presents a case study highlighting its applicability to rare earth metal solvent extraction.

10:50 AM  
Thermodynamic Modeling of Iron-copper-sulfuric Acid Solutions during Solvent Extraction and Electrowinning for Copper Production: Jiahao Xu1; Guikuan Yue1; 1University of Texas El Paso
    Solvent Extraction and Electrowinning (SX/EW) play an important role during the hydrometallurgical production of copper for low grade ores. To better understand the rapid Cu extraction/strip kinetics for producing a high-purity CuSO4-H2SO4 electrolyte and elucidate the method to maximize current efficiency by preventing leach carryover to electrolyte during SX and minimizing the iron concentration, a detailed speciation study is required to quantitatively describe the iron and copper distribution in the SX/EW solutions. In the present study, by virtue of our previous modeling work, thermodynamic modeling of the SX/EW solutions is carried out to quantify the distribution of iron (ferric and ferrous), copper and sulfuric acid. The developed model provides a mathematical tool capable of quantifying the concentrations of free ions and complexes in terms of temperature (25°C-60°C) and solution composition under simulated industrial conditions. Finally, oxidation reduction potential measurements are employed to validate the model.