Quasi-Chemical Viscosity Model for Fully Liquid Slag in the Al2O3-CaO-MgO-SiO2 System—Part I: Revision of the Model

Abstract

A model has been developed that enables the viscosities of the fully liquid slag in the multicomponent Al 2 O 3 -CaO-FeO-Fe 2 O 3 -MgO-Na 2 O-SiO 2 system to be predicted within experimental uncertainties over a wide range of compositions and temperatures. The Eyring equation is used to express viscosity as a function of temperature and composition. The model links the activation and pre-exponential energy terms in the viscosity expression to the slag internal structure through the concentrations of various Si 0.5 O, Me nþ 2=n O , and Me nþ 1=n Si 0:25 O viscous flow structural units (SUs). The concentrations of these SUs are derived from a quasi-chemical thermodynamic model of the liquid slag using the thermodynamic computer package FactSage. The model describes a number of slag viscosity features including the charge compensation effect specific for the Al 2 O 3 -containing systems. The predictive capability of the model is enhanced by the physical aspects of the model parameters-the correlation with other physicochemical properties as well as experimental viscosity data is used to determine model parameters. The present series of two papers outlines (a) recent significant improvements introduced into the model formalism and (b) application of the model to the Al 2 O 3 -CaO-MgOSiO 2 system, review of experimental viscosity data, and optimization of the corresponding model parameters for this system.

Viscosities of Iron Blast Furnace Slags

“…Selected BF viscosity models [13][14][15] are reproduced and calculated using the same compositions. The average relative deviations of the present model and other models are calculated and plotted in Fig.…”

“…Different viscosity models [12][13][14][15][16][17][18] have been proposed to predict the viscosities of BF slags in wide composition range. As significant discrepancies are present for the reported viscosity data, these viscosity models are yet to be developed to accurately predict the viscosities of BF slags.…”

Development of a Quasi-chemical Viscosity Model for Fully Liquid Slags in the Al2O3–CaO–‘FeO’–MgO–SiO2 System: The Revised Model to Incorporate Ferric Oxide

“…Experimental viscosity study in the Al 2 O 3 -'FeO'-SiO 2 slag at metallic iron saturation 12,13) showed possible maximum of viscosity at intermediate Al / (Al + Fe) ratios at constant SiO 2 concentrations indicating that the Fe 2+ cation possibly also introduces "the charge compensation effect", similar to the effects by the Ca 2+ and Mg 2+ in the Al2O3-containing systems. 10,11) In addition, noticeable charge compensation effect on the Fe 3+ cation in slags by basic cations such as Na + and Ca 2+ have been reported in previous viscosity experimental 14,15) and analytical 16) studies. Although several structurally-based viscosity models incorporate ferric oxide as chemical components in slag, [17][18][19][20] there is no description of the charge compensation effect on Fe 3+ .…”

“…The quasi-chemical viscosity (QCV) model and recent revisions have been presented in detail in previous publications; 1,10) a brief description of the essential features are given below.…”

“…The internal slag structure changes systematically with bulk slag composition and temperature, and is derived from the quasi-chemical thermodynamic model incorporated into the FactSage computer package. [5][6][7][8][9] Recently, a new significantly improved formalism of the QCV model has been reported by the authors, 10,11) which expresses a number of slag viscosity features systematically in a comprehensive manner superior to the previous version [1][2][3][4] and enables the viscosities of fully liquid slag in the Al 2 O 3 -CaO-MgO-SiO 2 system to be predicted within experimental uncertainties over a wide range of compositions and temperatures above liquidus. 10,11) This paper focuses on the effect of ferrous iron oxide and presents extension of the revised QCV model 10,11) to the Al 2 O 3 -CaO-FeO-Fe 2 O 3 -MgO-SiO 2 slag system close to and at metallic iron saturation as the first in a series describing the effects of both ferrous and ferric oxides on slag viscosity.…”