8th International Symposium on High Temperature Metallurgical Processing: Treatment and Recycling of Slag/Wastes
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
Thursday 8:30 AM
March 2, 2017
Location: San Diego Convention Ctr
Session Chair: Baojun Zhao, The University of Queensland; Matthew Andriese, Michigan Technological University
8:30 AM Introductory Comments
Introduction of Matte Droplets in Copper Smelting Slag: Xiangfeng Cheng1; Zhixiang Cui2; Leonel Leonel Contreras3; Mao Chen1; Anh Nguyen1; Baojun Zhao1; 1The University of Queensland; 2Dongying Fangyuan Nonferrous Metals; 3Codelco
Smelting is an important process in copper production to produce matte and slag which can contain 1-12% Cu. The slag can be further processed to recover the copper contaminated, but recycle of the slag concentrate reduces overall productivity and efficiency of the operation. The best solution is to minimize the Cu loss to the slag. The entrained matte droplets in copper smelting slag may originate from a few sources. The present study aims to investigate possible copper matte loss mechanisms by visualization of room temperature experiments and high-temperature examination. It is believed that the gas bubbles from the matte phase disperse the matte droplets into the slag causing entrained matte in slag. Analyses of quenched slags from an industrial operation and laboratory experiments confirmed that matte droplets in the slag are extensively associated with the gas bubbles. Water model is used to simulate the procedure and the bubble behaviors at the liquid-liquid interface are observed experimentally with a high-speed camera.
Dissolution Behavior of Fe from Glassy Oxide Phase in Steelmaking Slag: Shohei Koizumi1; Xu Gao2; Shigeru Ueda2; Shin-ya Kitamura2; 1Tohoku University; 2Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
Steelmaking slag is a useful fertilizer for paddy growth as it supplies Ca and Si to the soil water efficiently. In addition, to suppress the H2S generation in paddy soil, supplement of Fe from slag is expected. By our previous research, it was found that Fe is supplied mainly from CaO-SiO2-FeO glassy phase in slag. In this research, the glassy oxide of various composition was synthesized and investigated their dissolution behavior of Fe and the other cations into the aqueous solution of pH=5, which simulate the early stage of planting. The result showed that the dissolution ratio of Fe intensively increased with increasing the ratio of Fe2+/Fe3+, and showed local maximum by the change in basicity. This result is discussed by the glass structure considering the ratio of non-bonding oxygen.
Penetration Depth of Microwave in Tire Rubber: Yuzhe Zhang1; Jiann-Yang Hwang1; Zhiwei Peng2; Matthew Andriese1; Bowen Li3; Xiaodi Huang3; Xinli Wang1; Xin Yan1; 1Michigan Technological University; 2Michigan Technological University; Central South University; 3Michigan Technological University; Advanced Materials R&D Center of WISCO
Using a TM0n0 cavity system as the main reactor, an integrated process development unit was operated for finding the best condition of waste tire rubber absorbing microwave. The penetration depth was the main character for determining the best condition. The penetration depth is defined as the distance from the surface into the materials at which the traveling wave power drops to from its value at the surface. The waste tire powder was radiated by two different microwave frequency which is 915 MHz and 2466MHz with same powder size and same air condition. The effects of temperature and microwave frequency were analyzed based on the experimental data. The main trends are higher the temperature, the absorption will be better and higher the frequency, the better will be absorption.
Effect of FeO and CaO/SiO2 on the Degree of Metallization during Carbothermic Reduction of EAF Slags: Jongbae Kim1; Il Sohn1; 1Yonsei University
Electric arc furnace slags containing FeO-MgO-CaO-SiO2 reduced with carbon to identify the effect of FeO and CaO/SiO2. Lab scale reduction of FeO was done in an induction furnaceunder an Ar admosphere at 1773K. Molten pool of electrolytic iron was used to capture the reduced iron droplet from the FeO based slag by measuring the mass change of the iron pool. Degree of metallization of FeO was significantly affected by FeO concentration and CaO/SiO2. It was revealed that slag foaming and dispersed particles in the slag influenced the reduction phenomenon. Mass transfer coefficients of FeO in slag was calculated to understand and correlate the degree of metallization of FeO with the kinetics of the reaction.
Effect of TiO2 on Thermophysical Properties and Structure of P-bearing Steelmaking Slags: Zhanjun Wang1; Zuotai Zhang2; Mei Zhang1; Min Guo1; 1University of Science and Technology Beijing; 2South University of Science and Technology of China
In this study, the viscous flow and crystallization behavior of CaO-SiO2-MgO-Al2O3-FetO-P2O5-TiO2 steelmaking slags have been investigated over a wide range of temperatures. The results indicated that the viscosity of the slags decreased with increasing TiO2 content. The constructed non-isothermal continuous cooling transformation (CCT) diagrams revealed that the addition of TiO2 lowered the crystallization temperatures. This can mainly be ascribed that the addition of TiO2 promotes the formation of [TiO6]-octahedra units, thereby MgFe2O4-Mg2TiO4 solid solution is formed. Moreover, the decreasing viscosity has a significant effect on the diffusion of ion units, such as Ca2+ and [TiO4]-tetrahedra, from bulk melts to crystal-melt interface. The crystallization of CaTiO3 and CaSiTiO5 was therefore accelerated, which can improve the phosphorus content in P-enriched phase. Finally, the non-isothermal crystallization kinetics was characterized and the activation energy for the primary crystal growth was derived.
10:15 AM Break
Analysis for Optimum Conditions for Recovery of Valuable Metals from E-Waste through Black Copper Smelting: Mohammad Al Hossaini Shuva1; M Akbar Rhamdhani1; Geoffrey A Brooks1; Syed Masood1; Markus A Reuter2; Muhamad Firdaus1; 1Swinburne University of Technology; 2Helmholtz Institute Freiberg for Resource Technology
Declining grade of primary ores and resource efficiency have led us to process more alternative metal resources such as e-waste. One of the processing routes for extracting valuable metals from e-waste is through the black copper smelting. However, the underlying knowledge of the thermodynamics behaviour of the valuable metals contained in e-waste during smelting are limited which prevent us from developing an optimised process to recover all the metals. These different metals clearly will have different favourable conditions for their extraction. To illustrate this, the distribution behaviour of germanium (Ge) and palladium (Pd) between liquid copper and ferrous-calcium-silicate slag during black copper smelting was analysed. It was demostrated that oxygen partial pressure and slag composition affect the partitioning of these metals to the copper phase and that the favourable slag chemistry for recovering these metals is opposing. Considering the available thermodynamic data of these metals, an analysis for the optimum conditions is presented.
The Reduction of Chromite or Chromium Slag with Silicon Wafer Kerfloss: Jong Ho Kim1; 1Research Institute of Industrial Science and Technology
Silicon wafer kerfloss is produced during silicon wafer slicing process of solar grade silicon ingot. Silicon wafer kerfloss contains silicon particles, silicon carbides, and cutting lubricants. The separation of lubricants from kerfloss is relatively easy but separating silicon and silicon carbide is a big challenge. In this study, the way of utilizing kerfloss is proposed as the reduction of chromite or chromium slag. Chromite is conventionally reduced by carbon in an arc furnace and chromium slag is reduced by ferrosilicon in the stainless steel making process. Prior to experimental work, thermodynamic calculation was conducted by commercial software and its possibility of reducing reaction was evaluated, then reduction experiments were carried out in a vertical tube furnace. In results, chromite and slag were successfully reduced by silicon kerfloss and the fabrication of ferrochrome was confirmed by slag/metal characterizations.
Precipitation Behavior of MxTi3-xO5 in the Titanium-Bearing Electric Furnace Slag: Fuqiang Zheng1; Xiaoming Qu1; Guanzhou Qiu1; Yufeng Guo1; Tao Jiang1; 1Central South University
MxTi3-xO5 is the main titanium-bearing mineral in titanium-bearing electric furnace slag (TEFS), which is produced by direct reduction-electric furnace smelting process with vanadium titanomagnetite concentrate in Panzhihua-Xichang region of China. In order to effectively utilize the titanium resource in TEFS, the thermomechanical analysis and conditions for the growing up of MxTi3-xO grain was investigated, which emphasis on the effect of CaF2 and cooling rate on the crystallization of MxTi3-xO5 in the melting process. The mineral phase and morphology of titanium-bearing slag were determined by XRD and optical microscope technique, respectively. The results indicated that the average grain size of MxTi3-xO5 grown up from 30 μm to more than 70 μm and the volume fraction of MxTi3-xO5 reached about 55 % from 25 % under the conditions of 5 wt.% CaF2 and cooling rate at 1 °C/min.
Research on the Slag Type of Laterite Ores Smelting Reduction: Liu Chang1; 1Shanghai University
This paper suggested a process that high nickel (Ni > 25%) alloy was produced by laterite ores smelting reduction in the condition of high oxygen level. In order to find the slag type used for this process, the metallurgical properties of FeO-SiO2-CaO-MgO slag system were studied by consulting the slag phase diagram, thermodynamic calculation and laboratory experiments. The results showed the slag, contained CaO 20-23 wt%, FeO 15-15 wt%, MgO 19-21 wt%, SiO2 38-42 wt%, has lower melting temperature range (1543-1573 K) and suitable viscosity. The smelting experiment indicated that the recovery ratio of Ni was more than 95%, and the content of NiO in the slag can be decreased to less than 0.15%. This will create a new way to utilize laterite ores.