12th International Symposium on High Temperature Metallurgical Processing: On-Demand Poster Session
Sponsored by: TMS Extraction and Processing Division, TMS: Pyrometallurgy Committee
Program Organizers: Zhiwei Peng, Central South University; Jiann-Yang Hwang, Michigan Technological University; Jesse White, KTH Royal Institute of Technology; Jerome Downey, Montana Technological University; Dean Gregurek, RHI Magnesita; Baojun Zhao, Jiangxi University of Science and Technology; Onuralp Yücel, Istanbul Technical University; Ender Keskinkilic, Atilim University; Tao Jiang, Central South University; Morsi Mahmoud, King Fahd University of Petroleum & Minerals

Monday 8:00 AM
March 14, 2022
Room: Materials Processing
Location: On-Demand Poster Hall

Disintegration Behavior of Vanadium–titanium Magnetite Pellets in Gas Mixtures of CO–H2–CO2–N2: Yue Wang1; Jianbo Zhao1; Donglai Ma1; Qingqing Hu1; Yongjie Liu1; Zhixiong You1; 1Chongqing University
    Vanadium–titanium magnetite (VTM) is a polymetallic symbiotic mineral which primarily contains iron, vanadium, titanium, and other valuable elements such as chromium, cobalt, nickel, etc. VTM is generally sintered or pelletized for iron making process. Under the worldwide trend of low-carbon metallurgy, hydrogen (H2) is a potential option for a further reduction of CO2 emission in both blast furnace (BF) and non-blast furnace iron making processes. H2 promotes the reduction of iron-bearing burden, but its influence on their reduction disintegration behavior deserves investigation in detail, especially for VTM burden. In this study, the disintegration behavior of VTM pellets in gas mixtures of CO–H2–CO2–N2 was investigated. The effect of gas composition, reducing temperature as well as reducing time on disintegration index was studied. The reduced samples were observed by an optical-microscope and an electron probe micro-analyzer for evaluation of reaction mode. Further, the reaction mechanism was also discussed.

Effect of Channel Heights on the Flow Field, Temperature Field and Inclusion Removal of Induction Heating Tundish: Xi-qing Chen1; Hong Xiao1; Pu Wang1; Peng Lan1; Hai-yan Tang1; Jia-quan Zhang1; 1University of Science & Technology Bejing
    The influence of channel height on the flow, heat transfer and inclusions removal behaviour of the dual-channel six-strand induction heating (IH) tundish is analysed by establishing a three-dimensional coupled electromagnetic-flow-thermal numerical model and the Lagrangian Discrete Phase Model. The results show that as the channel height increases, the molten steel at the exit of channel with IH changes from a significant downward flow to an upward flow, but the level fluctuates too sharply at 500 mm. Compared with the condition of IH turned off, the inclusion removal ratio of channel heights for 300mm, 400mm and 500mm under IH increased by 10.13%, 14.27% and 12.38%, respectively. It is suggested that the channel height of 400 mm not only can avoid the short-circuit flow tendency of the strand 2 and improve the inclusions removal ratio, but also it will reduce the risk of slag entrapment by excessive liquid level fluctuations.

Experimental Study on Thermal Shock Resistance of Magnesia Carbon Brick: Changhai Lv1; Jing Li1; Renxiang Lv2; Shouxin Tian3; 1University of Science and Technology Beijing; 2Jinan Ludong Refractories Company; 3Baosteel Group Central Research Institute
    In this paper, 5 kinds of magnesia-carbon refractories commonly used in the metallurgical industry were selected for thermal shock resistance study. The experiment results showed that the maximum residual flexural strength of sample 2#, with the best thermal shock resistance by standard, was 8.07 MPa after three thermal shock cycles under the stress of not more than 0.3 MPa. The accuracy of this result was verified through the linear expansion rate and high-temperature Re/E index test. The linear expansion rate of sample 2# basically chimed with that of the high carbon sample at the test temperature of 1200 ℃-1500 ℃, with superior high-temperature Re/E index of sample 2#. The comprehensive analysis suggested the best thermal shock stability of sample 2#. Therefore, this type of magnesia carbon brick with 14% carbon can meet the requirements for the use of refractory materials in a converter bath.

Changes of SO2, NOx Emission and Production of Iron Ore Sintering with Steam Injection at the Surface of Sintering Bed: Yapeng Zhang1; Wen Pan1; Shaoguo Chen1; Huaiying Ma1; Jingjun Zhao2; Zhixing Zhao1; Huayang Liu2; 1Shougang Group Co., LTD Research Institute of Technology; 2Shougang Jingtang United Iron &Steel Co., Ltd
    The effect of steam injection on emission reduction and the quality index of sintering were studied. The sintering cup test showed that steam injection on the sintering bed surface has the effect of reducing NOx. It was also beneficial to reduce fuel consumption and the emission of SO2. After steam injection, the sinter drum index is slightly increased, the solid fuel consumption in sintering reduced by 1.64kg/t, and the ratio of 5-10mm sintered ore reduced by 0.8%. The steam injection improved the sinter quality and reduce the solid fuel consumption. Furthermore, the effect of steam injection in the middle part of sintering process was the most significant.

Study on Burden Mineral Phase Identification System and Prediction Model of Metallurgical Properties Based on BP Neural Network: Qingqing Hu1; Donglai Ma1; Yue Wang1; Zhixiong You1; Xuewei Lv1; 1Chongqing University
    Sinter and pellet are the main burden of blast furnace ironmaking process, and their phase composition plays an important role on the metallurgical properties. It is of great significance to investigate the influence of phase composition on metallurgical properties. In this paper, based on the optical micrographs and image analysis, the gray range of each mineral is preliminarily determined. Then, the composition and content of different mineral in burden can be calculated by reflectance calculation model. Furthermore, BP neural network method is used to study the mapping relationship between mineral phase composition and metallurgical properties. A high-precision prediction model of burden mineral phase-metallurgical properties is established, and the influence of the content of each phase on metallurgical properties is qualitatively analyzed. The model has reached a certain accuracy, and in order to improve the accuracy of the model, it is necessary to enrich the database and improve the modeling method.

Effect of Slag Basicity on Non-metallic Inclusions in a Heavy Rail Steels: Nan Liu1; Lifeng Zhang2; Yanping Chu1; Ying Ren1; 1University of Science and Technology Beijing; 2Yanshan University
    Experiments and thermodynamic calculations were performed to investigate the effect of slag basicity (CaO/SiO2) on non-metallic inclusions in heavy rail steels. With the increased of slag basicity from the 1.7 to 2.3, the composition of inclusions changed from the SiO2-CaO to Al2O3-MgO-SiO2-CaO. During the rolling process, the full liquid inclusions was rolled to the linear shape inclusions. It was proposed that the target of inclusions was the partial liquid inclusions instead of the full liquid inclusions to avoid the formation of the linear shape inclusions. Moreover, the relationship between the composition of the Al2O3-MgO-SiO2-CaO slag and the composition of inclusions was calculated using FactSage thermodynamic software. The content of Al2O3 in inclusions increased from less than 10 % to above 30 % with a higher slag basicity. The Al2O3 content in slag should be lowered as low as possible to reduce the Al2O3 content in inclusions in heavy rail steels.

Distribution of Inclusions in an IF Steel Continuous Casting Slab Casted during SEN-Clogged State: Qiuyue Zhou1; Rikang Huang1; Lifeng Zhang2; 1University of Science and Technology Beijing; 2Yanshan University
    Inclusions in IF steel slab were detected to investigate the distribution of inclusions in Slab under the nozzle clogging state. The endogenous inclusions in IF steel were Al2O3 inclusions, TiN inclusions were precipitated with Al2O3 as the core during the cooling process of slab. In the thickness direction from the surface to the center of the slab, the area fraction of inclusions increased from 25.32 ppm to 267.78 ppm, the maximum value of inclusion area fraction was 405.62 ppm below the center of the slab. Due to the small cooling rate at the center of the slab, the number density of TiN larger than 10um reached 1.64 #/mm2. Under the condition of nozzle clogging, the level fluctuation is large in the mold, contrary to the normal condition, the number density of inclusions on the loose side of the slab was larger than the fixed side.