8th International Symposium on High Temperature Metallurgical Processing: Energy Efficient Clean Metallurgical Technology
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 AG; Ender Keskinkilic, Atilim University
Monday 9:20 AM
February 27, 2017
Location: San Diego Convention Ctr
Session Chair: Jiann-Yang Hwang, Michigan Technological University; Zhiwei Peng, Central South University
9:20 AM Introductory Comments
Flash Ironmaking from Magnetite Concentrate in a Laboratory Reactor: Experimental and CFD Work: Mohamed Elzohiery1; De Qiu Fan1; Yousef Mohassab1; H.Y. Sohn1; 1University of Utah
A flash ironmaking process is being developed at the University of Utah in which iron is produced directly from magnetite concentrate. The kinetics of magnetite reduction by a mixture of H₂ and CO gases was determined in the temperature range 1150-1600 °C. Over 90% reduction degree was achieved at a temperature as low as 1250 °C within 4-6 seconds which is the typical residence time available in a flash reactor. The kinetics results were applied to experimental data obtained in a laboratory flash reactor in which H₂ and CO gas mixtures were produced from in situ partial oxidation of natural gas with oxygen. CFD was used to simulate the laboratory reactor, and the results were in good agreement with the experimental data.
Synthesis of Chromite for Subsequent Carburization by Methane-hydrogen Gas Mixture: Vincent Canaguier1; Leiv Kolbeinsen1; Ingeborg-Helene Svenum2; 1Norwegian University of Science and Technology; 2SINTEF Materials and Chemistry
The purpose of this work was to produce synthetic chromite in order to assess the influence of the chromite composition on the carburization process. Thus, pelletized and sintered synthetic chromite samples from the (Fe,Mg)(Cr,Al)2O4 system were prepared by induction skull melting of pure reagents. The optimal conditions for the synthesis were considered. The pellets were later reduced and carburized using Ar-H2-CH4 gas mixtures with high carbon activity at elevated temperatures in both isothermal and non-isothermal experiments. The reaction starting temperature, reaction extent, the graphite formation and the off-gas composition were evaluated. The product phases after both synthesis and carburization were identified using X-Ray Diffraction (XRD) analysis, X-ray Photoelectron Spectroscopy (XPS) and oxygen analysis. The microstructure was analyzed by Scanning Electron Microscope (SEM) and Electro-Probe Micro-Analysis (EPMA). The effects of Al and Mg on the synthesis route and on the reduction/carburization reaction mechanisms are discussed.
10:05 AM Break
Effects of Hydrogen-enriched Reduction on Metallurgical Properties of Iron-bearing Burdens under BF Operation with Cog Injection: Hongtao Wang1; Mansheng Chu1; Chuanguang Bi2; Zhenggen Liu1; 1Northeastern University; 2Shanghai Meishan Iron and Steel Corporation Ltd
COG injection is considered as one of effective measures to reduce carbon emission of BF. The BF operation with COG injection was simulated by means of multi-fluid BF mode，which revealed that with increasing COG injection rate, in-furnace H2 concentration is increased and reduction of magnetite and wustite by H2 is obviously accelerated. Under this hydrogen-enriched condition, metallurgical properties of iron-bearing burdens were experimentally investigated. The GB/T13242-91 test results showed that with 152.34 m3/tHM COG injection, the reduction swelling index of pellets is decreased from 10.71% to 9.54% while reduction ratio is increased from 31.57% to 36.39%. Softening interval of mixed burdens is increased from 163.6℃ to 228.3℃ while melting interval is decreased from 147.3 ℃ to 92.4 ℃. The cohesive zone moves downwards and becomes narrower. The permeability of mixed burdens is improved. In terms of metallurgical properties of iron-bearing burdens, COG injection benefits to improve BF performance.
Investigations on Matrix Reactivity towards the Efficiency of the LSI Process: Simge Tülbez1; Arcan Dericioglu1; 1Middle East Technical University
In recent years, usage of carbon fiber-reinforced silicon carbide (C/SiC) matrix ceramic composites has increased considerably because of their high temperature mechanical properties in addition to their erosion and thermal shock resistance along with low weight compared to their counterparts. The current study was undertaken to investigate the production and characterization of these composites via Liquid silicon infiltration (LSI) method. In the scope of the present study, in order to understand the mechanism and kinetics associated with SiC formation by LSI process, different alternative matrix materials in powder form was infiltrated with liquid silicon at 1650 °C and in vacuum.
Refractory Challenges in Lead Recycling Furnaces: Dean Gregurek1; Katja Reinharter1; Viktoria Reiter1; Christine Wenzl1; Alfred Spanring1; 1RHI AG
The refractory linings in lead furnaces are exposed to several stresses rather complex in their interaction. In the present study the magnesia-chromite brick out of a lead recycling furnace suffered from a high chemical attack by the process slag. The high CaO, BaO and sulfur bearing silicate slag, as well as a high Na2O supply from soda resulted both in a deep-reaching infiltration of the brick microstructure and a severe corrosion of the brick components. Both the sintered magnesia and chromite were attacked chemically. The FactSage calculations showed the formation of high amounts of liquid phase in the infiltrated microstructure. Further phenomena affecting the refractory performance such as iron oxide attack, redox effects, and boron attack are also discussed in the paper. The obtained information and insights serve as a basis for improving refractory materials (i.e., choice of refractories for individual process and new developments) and consequently furnace operations.
Synthesis of Carbide Ceramics via Reduction of Adsorbed Anions on an Activated Carbon Matrix: Grant Wallace1; Jerome Downey1; Jannette Chorney1; David Hutchins1; Alaina Mallard1; 1Montana Tech of the Univ of MT
Current commercial metal carbide production processes require temperatures above 1700oC and often use extensive milling operations to produce a powder product. A process that could reduce the energy requirements of commercial carbide production would reduce operating costs, allowing these materials to be implemented in a greater number of applications. This study examined carbide production via carbothermal reduction and carburization under inert and reducing gas atmospheres. Precursor materials were formed by adsorption of silicate (SiO32-) anions and tungstate (WO42-) anions onto activated carbon. The anions were converted into silicon carbide (SiC) whiskers and a mixture of tungsten and tungsten carbide (W/WC/W2C) crystals at 950oC and 1400oC, respectively. The adsorption process was statistically optimized via a central composite response surface analysis using DesignExpert 9. Inductive coupled plasma optical emission spectroscopy (ICP-OES) was used to measure and optimize adsorption efficiency; carburization products were characterized using X-ray diffraction and scanning electron microscopy.
Metals and Mattes Air Atomization: A New Method to Increase Productivity: Sina Mostaghel1; Lily Lai Chi So1; Santiago Faucher1; Mahdi Mahdi1; Daan Sauter1; 1Hatch Ltd.
The necessity to maintain materials in molten state, for transfer and/or energy consumption management leads pyrometallurgcial operations to have coupled unit processes. For example, copper smelting and converting, where no other holding capacity exists between these units except for what matte hold-up time the furnace can offer. Thus in this process, upsets in downstream equipment ultimately leads to shut down of the smelting furnace. The same coupling exists in some other base metal smelting and even Ironmaking/steelmaking processes. Metallurgists have thus sought ways to decouple these unit processes in order to increase the plant’s availability and thereby productivity; however, the existing solutions (casting, water granulation, ladles, etc.) are generally associated with a number of difficulties for the operators and are not very efficient for some plants; hence, have not been widely adopted. The current article introduces a practical and piloted solution to this dilemma: air atomization of mattes and metals.