Quasi-Chemical Viscosity Model for Fully Liquid Slag in the Al2O3-CaO-MgO-SiO2 System. Part II: Evaluation of Slag Viscosities

Abstract

A model is presented that enables viscosities to be predicted reliably over the whole range of compositions and temperatures in the Al 2 O 3 -CaO-MgO-SiO 2 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 charge-compensation effect of the Ca 2+ and Mg 2+ cations on the formation of tetrahedrally coordinated Al 3+ was introduced. Parameters of the quasi-chemical viscosity model have been optimized to reproduce within experimental uncertainties most of the selected experimental data in the Al 2 O 3 -CaO-MgO-SiO 2 system and all subsystems. This study is part of the overall development of the self-consistent viscosity model of the Al 2 O 3 -CaO-FeO-Fe 2 O 3 -MgO-Na 2 O-SiO 2 multicomponent slag system.

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+ .…”

“…To improve reproducibility of reliable experimental viscosity trends for a wide composition range, the model has been critically reviewed and subsequently revised; 10,11) the partial properties a,pq and ε V, pq of a given structural unit (Me p -O-Me q ) are described with Eqs. (6)- (8) (8) and (8') is a probability function that expresses the probability to have a tetrahedrallycoordinated Al 3+ or Fe 3+ among existing (Am k -O-Me s ) and (Amj-O-Mes) structural units (the symbol "Am" corresponds to Amphoteric oxide);…”

“…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.…”

Accurate Density Calculation for Molten Slags in SiO₂–Al₂O₃–CaO–MgO Systems

“…The densities of CaO and MgO in solid state are expected to be higher than in liquid states, thus it would be interesting to compare the predicted liquid density to the According to the results shown in Table 5 Table 4), as well as the similar effect on viscosity of the complex charge compensation of tetrahedrally coordinated Al 3 + by Ca 2 + or Mg 2 + cations. 72,73) Using current density model, the density curves for binary systems of SiO 2 -M and Al 2 O 3 -M at 1 773 K and 1 873 K were calculated, as shown in Fig. 6.…”

Operation Characteristic of Super-Large Blast Furnace Slag in China

“…These viscosity models can be generally classified into two groups, empirical models and structural models. [7][8][9][10][11][12] The Multi-Phase Equilibrium (MPE) is a thermodynamic package developed by CSIRO for simulating reactions between phases in multi-component and multiphase systems. [13][14][15] Through application of the thermodynamic model MPE, the viscosity and liquidus temperature of BF slags were calculated and compared with published experimental data.…”