2014-Sustainable Industrial Processing Summit
SIPS 2014 Volume 6: Rare Earths & Ionic Liquids
| Editors: | Kongoli F |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2014 |
| Pages: | 432 pages |
| ISBN: | 978-1-987820-08-9 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Rheological characteristics of molten ionic slag having network structure
Kakali Mukherjee1;1CSIR-NATIONAL METALLURGICAL LABORATORY, Jamshedpur, India;
Type of Paper: Regular
Id Paper: 140
Topic: 11
Abstract:
Molten blast furnace slag systems viz Al2O3, SiO2, CaO, FenO, MgO, MnO etc. are comprised of ionic network structure. These slag systems possess silicate network structure. Silicate slags are built up of Si4+ cations, surrounded by 4 oxygen anions in the form of a regular tetrahedron. These (SiO4)4-tetrahedra are joined together in chains or rings by bridging oxygen. The mobility of ionic species present in the slag affects the slag rheology. However, the mobility is, in turn, dependent on the nature of the chemical bond, inter-ionic forces of the ions involved. The stronger inter-ionic forces leads to higher slag viscosities. The paper examines slags possessing high silica contents and discusses the effect of its polymeric anions on the rheology of slag system. It shows that as the metal oxide concentrations increase, Si-O bonds break down and decrease the slag viscosity. In high alumina blast furnace slags; alumina is present as (AlO4)5-forming polymeric units with (SiO4)4. Thus, alumina acts as a network former. The cations of basic oxides viz lime, magnesia, titania act as a network breakers and oxygen providers. They result in de-polymerization of the melt and the basic cations tend to balance the charges to maintain the electrical neutrality. This phenomena interestingly affects the slag rheology. The paper discusses the effect of alumina on the slag viscosity at high temperatures. The ionic network structure of the slag determines the heat levels in the blast furnace operations to maintain the adequate slag rheology. The paper discusses the high temperature rheological experimentation of some molten blast furnace slag containing high alumina and its effect in slag rheology. The paper also describes some results of a model study of the momentum transfer to the blast furnace slag systems possessing ionic network structure.