Authors: Masanori Suzuki Evgueni Jak
Publish Date: 2013/10/01
Volume: 44, Issue: 6, Pages: 1451-1465
Abstract
A model is presented that enables viscosities to be predicted reliably over the whole range of compositions and temperatures in the Al2O3CaOMgOSiO2 slag system above liquidus in the temperature range from 1543 K to 2643 K 1270 °C to 2370 °C Experimental procedures and data from the studies reported in the literature have been collected and critically reviewed with particular attention to the viscometry methods and possible contamination of slag samples to select reliable data points for further model development Relevant revised formalism to describe the complex viscosity trends including chargecompensation effect of the Ca2+ and Mg2+ cations on the formation of tetrahedrally coordinated Al3+ was introduced Parameters of the quasichemical viscosity model have been optimized to reproduce within experimental uncertainties most of the selected experimental data in the Al2O3CaOMgOSiO2 system and all subsystems This study is part of the overall development of the selfconsistent viscosity model of the Al2O3CaOFeOFe2O3 MgONa2OSiO2 multicomponent slag systemA previous article1 in this series of two presented the revised formalism of the quasichemical viscosity model2 3 4 5 6 7 This work is undertaken as part of the overall development of the selfconsistent viscosity model of the Al2O3CaOFeOFe2O3MgONa2OSiO2 multicomponent slag system The current article outlines development of the revised viscosity model1 for the Al2O3CaOMgOSiO2 slag system which is a key slag system for a number of metallurgical processes including ironmaking and steelmaking A number of viscosity measurements has been carried out for this system8 9 10 11 12 13 14 15 16 17 18 19 20 21 and its subsystems22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 A critical review of experimental procedures and selection of reliable experimental data is an essential stage of the model development The procedures involved in optimization of the model parameters are reported The comparisons between the viscosities predicted with the current model and selected reliable experimental data demonstrate agreements within experimental uncertainties over a wide range of temperatures and compositions above liquidusThe viscosities in this Al2O3containing system have complex trends in particular they have the characteristic maximum at the Me n+2/n O/Al2O3 ratios around 1 Particular focus in the current article therefore was given to the description and analysis of this characteristic maximum which is attributed to the socalled “chargecompensation effect” commonly explained by the ability of the Al3+ cation to take tetrahedral interstitial between the oxygen anions if the excess negative charge for Al3+ is compensated with alkali or alkaline earth cations such as Ca2+ and Mg2+ and therefore by the formation of the stronger AlOMetal covalent bonds This characteristic maximum was described in the present formalism through the introduction of the probability function expressing proportion of the tetrahedrally coordinated Al3+containing viscous flow structural units The Eyring equation40 41 42 was used in the current quasichemical viscosity model1 2 3 4 5 6 7 it proved to be adequate to develop a reliable viscosity model to reproduce complex viscous behavior of slag systems The viscosity equation and parameters for the Al2O3CaOMgOSiO2 slag and its subsystems and the detail optimization procedures of these parameters are presented in our previous article1 of this series of two articles These model parameters have been optimized using the available experimental viscosity data and some correlations with other physical properties
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