8th International Symposium on High Temperature Metallurgical Processing: Fundamental Research of Metallurgical Process
Sponsored by: TMS Extraction and Processing Division, TMS: Pyrometallurgy Committee
Program Organizers: Jiann-Yang Hwang, Michigan Technological University; Tao Jiang, Central South University; Mark Kennedy, Proval Partners SA; Onuralp Yücel, ITU; P. Chris Pistorius, Carnegie Mellon University; Varadarajan Seshadri, Universidade Federal de Minas Gerais; Baojun Zhao, The University of Queensland; Dean Gregurek, RHI Magnesita; Ender Keskinkilic, Atilim University
Tuesday 8:30 AM
February 28, 2017
Location: San Diego Convention Ctr
Session Chair: Mark Kennedy, Proval Partners SA; Xuewei Lv, Chongqing University
8:30 AM Introductory Comments
Kinetics of Dephosphorization between Bloated Metal Droplet and Slag Containing Iron Oxide: Kezhuan Gu1; Kenneth Coley1; Neslihan Dogan1; 1McMaster University
A detailed study on dephosphorization kinetics is important for better understanding the role of bloated metal droplet in refining reactions during oxygen steelmaking. In present work, dephosphorization behavior of droplets with 0.007wt% and 0.021wt% sulfur were studied using X-ray fluoroscopy technique at temperature ranging from 1813K to 1913K. The experiment results indicated that dephosphorization of metal droplets in foaming slag is slower than it in dense slag due to the lower mass transfer coefficient of FeO and the small liquid slag volume in the foam. It was also suggested that internal decarburization offers a higher mass transfer coefficient due to the faster surface renewal rate, leading to a higher dephosphorization rate. In addition, dephosphorization behavior for droplets without carbon was also investigated to elucidate the effect of CO bubble formation on dephosphorization kinetics.
Kinetic Study of Low Grade Nickel Ores by Pyrometallurgical Processes: Sandra Diaz1; Oscar Restrepo1; 1Universidad Nacional de Colombia
The extraction of nickel has been from sulfides and silicates ores, this extraction now is made from low grade nickel ores, because the nickel content has decreased considerably. These ores are processed by pyrometallurgical processes. Nowadays, the study of these ores is necessary in order to give a great understanding when these type materials are processed. In this study, it is given an alternative activation energy process, the mechanism possible that it is presented, and recovery percentage of nickel and iron metallic. A sample with 1.42% nickel was used. This sample was processed, it was obtained ferronickel to 1450, 1500 and 1550°C. The ferronickel slags were characterized by diffraction ray X, atomic absorption and scanning electronic microscopy, in order to obtain the amount nickel and iron, lost in the slag. The recovery of nickel and iron was above 90% in ferronickel percentage.
Investigate on the Phase Composition of Vanadium Slag with High CaO Content and Influence of P2O5 on Crystallization Kinetics of Spinels: Wang Zhou1; Bing Xie1; Zhao-Qun Ke1; Jiang Diao1; Wen-Feng Tan1; Yu-Hao Liu1; Hong-Yi Li1; Tao Zhang1; 1Chongqing University
An effective way to decrease the dephosphorization burden in the current vanadium extraction-steelmaking process is adding CaO into the vanadium extraction step. The phase composition of vanadium slag with different basicity and the regularities distribution of elements have been investigated by X-ray diffraction analysis and scanning electron microscopy combining with energy disperse X-ray spectrometry (SEM/EDS), respectively. The results indicate that V mainly concentrates in the spinel phases; Ca and P are rich in the silicate phases. While the basicity of vanadium slag is 1.3, Fe2SiO4 transform to CaFeSiO4. With further increase of basicity, 2CaO·SiO2 could form in the silicate phases. Moreover, the phosphorus-containing phase will transform from Ca3(PO4)2 to Ca3(PO4)2-Ca2SiO4. With the increase of P2O5 content, the crystallization rate of spinels decrease obviously. Furthermore, the peak temperature for crystallization of spinels decrease 5K with P2O5 content increasing 1wt%.
Effect of Carbon to Hematite (Fe2O3) Molar Ratio on the Reduction Behaviour of Iron Ore-coal Composite Pellets in Multi-layer Bed Rotary Hearth Furnace (RHF): Srinibash Mishra1; Gour Gopal Roy2; 1Indian Institute of Technology Kharagpur; 2Indian Institute of Technology Kharagpur
Effect of carbon to hematite molar ratio has been studied on the reduction behaviour of iron ore-coal composite pellets reduced at 1250°C for 20 minutes in a laboratory scale multi-layer bed Rotary Hearth Furnace (RHF). Reduced pellets have been characterized through the measurement of degree of reduction, metallization, porosity, shrinkage, phase analysis by XRD, and compressive strength. Pellets with optimum carbon to hematite molar ratio (C/Fe2O3 = 1.66) that is much below the stoichiometric carbon required for direct reduction of hematite yielded maximum reduction, better carbon utilisation, and productivity. Top layer exhibited higher reduction at comparatively lower carbon level (C/Fe2O3 <2.33) in the pellet; while bottom layer exceeded top layer at higher carbon level (C/Fe2O3 >2.33). Compressive strength of the partially reduced pellet with optimum carbon content (C/Fe2O3 = 1.66) showed that they could be potentially used as an alternate feed in a blast furnace or any other smelting reactor.
The Kinetics Study on the Reaction Rate Constant of Pulverized-coal Combustion at Different Heating Rates: Ruiling Du1; 1University of Science and Technology Beijing
The technology of coal injection is widely used in blast furnace ironmaking. The pulverized-coal combustion is crucial to reduce the consumption of energy. The combustion performance varies with different heating conditions. Therefore, the influence of heating rate on the combustion kinetic of pulverized-coal was studied. Generally, the kinetic compensation effect for different heating rates is expressed as lnAi=aEai+b.The influence of heating rate β on activation energy Eai can be described as Eai=△Ealnβi+Ea0. Then, the Arrhenius equation is modified as lnki=-Ea0/RT+△Ea(a-1/RT)lnβi+lnA0 to describe the influence of heating rate β on the rate constant k of pulverized-coal combustion. Finally, the extrapolation reliability of the modified Arrhenius equation is validated by other different heating rates. The results show that the modified Arrhenius equation is not only the most expedient way to depict the combustion kinetic at different heating rates, but also provides extrapolation reliability over a broad range.
10:15 AM Break
Evaluation of High Temperature Refractory Corrosion by Liquid Al2O3-Fe2O3-MgO-SiO2: Christoph Sagadin1; Stefan Luidold1; Christine Wenzl2; Christoph Wagner2; 1Montanuniversitaet Leoben; 2RHI AG
Corrosion mechanism have been investigated between MgO refractory substrates and FeNi slags. The slags taken into consideration comprised a simple synthetically mixed slag with specific oxides and a real slag from a ferroalloy producer. The MgO refractory substrates with the slag specimens on it were heated in a hot stage microscope to three different characteristic temperatures. The experiments proceeded under a controlled gas atmosphere that simulates the relevant process conditions. The corrosion mechanisms of each system were determined by SEM analyses. The obtained results showed that slag corrosion is dominating with a pronounced partial dissolution of refractory. It was also observed that iron oxide present in the slag diffused into the coarse refractory grains forming the relative low melting magnesia wuestite. Finally, the comparison of these findings with those predicted by thermodynamic calculation (FactSage) indicated the corrosion mechanisms and draw implications for improving the refractory performance and lifetime.
Thermodynamic Calculation on the Reactivity between Slag and Ti-stabilized Stainless Steel: Zhuo Chen1; Kun-peng Xu1; Sheng-ping He1; Qian Wang1; 1Chongqing University
During the continuous casting (CC) process of Ti-Stabilized Stainless Steel, the nozzle clogging or even the crusts composed of TiN, Al2O3, TixOy and the complex inclusions MgO•Al2O3, Al2O3 enwrapped by TiN is often occured. The main objective of the present study is to research the reaction between refining slag or mould fluxes and Ti-Stabilized Stainless Steel by thermodynamic calculation. A suitable refining slag composition was sought to absorb Al2O3 ,TixOy inclusions, and the reactions between different mould fluxes and steel were calculated and compared. It was found that a suitable refining slag was difficult to adjust aluminum and titanium to meet requirement simultaneously. The components,SiO2, Fe2O3, Na2O and B2O3 of mould fluxes would react with titanium in the steel. The CaO-SiO2 based mould fluxes had a stronger reactivity than CaO-SiO2 -Al2O3 and CaO-Al2O3 based mould fluxes.
11:15 AM Cancelled
Phase Equilibria and Thermodynamics of CaO-SiO2-Dy2O3 System: Fei Wang1; Thu Hoai Le2; Bin Yang1; Muxing Guo2; 1Kunming University of Science and Technology; 2Kunming University of Science and Technology Leuven
The thermodynamics of Dy2O3 containing metallurgical slag system at high temperature (including phase relations of the slag at high temperature and precipitation of the REEs containing solid compounds during cooling) were investigated in this paper experimentally. Phase equilibria of CaO-SiO2-Dy2O3 system were obtained at 1773 K and 1873 K for 24 h in Ar, and then quenched in water to determine the phase relations. The crystallography and microstructural studies of phase transformations in the system were determined by EPMA-WDS and EBSD, respectively. The isothermal section of the phase diagram was constructed to target a new approach for the concentration and separation of rare earth elements and their transformation into metallic form from rare earth slags or recycled rare earth concentrates.