A Study on the Viscous Behaviour with K₂O Additions in the CaOSiO₂Al₂O₃MgOK₂O Quinary Slag System

Abstract

The viscosities of CaOSiO220wt%Al2O310 wt%MgO‐K2O quinary slags with CaO/SiO2 from 0.8 to 1.2 at 1773 K with 1–5 wt% K2O additions were measured to estimate the effect of K2O on the viscous behaviour of the slags. The measured viscosity at 1773 K increased with K2O addition at a fixed CaO/SiO2, which is contrary to the effect of Na2O on the viscosity of BF slags. To qualitatively verify the changes in slag structure, FT‐IR spectroscopy was used. It was found that K2O induces Al2O3 to behave as an acidic oxide by forming [AlO4]5−‐tetrahedral units by the ionic compensation effect of K+ cations. However, regarding the effect of K2O on the silicate structure, it is observed that K2O has a negligible effect due to the consumption of O2− with the formation of [AlO4]5−‐tetrahedral units. Furthermore, it is also found that SiOAl bending became more complicated with K2O additions, which supports the selective effect of K2O on the aluminate structure of the slag. In spite of the more complicated structure with K2O additions, the critical temperature (TCR) decreased due to the gradual reduction of the liquidus temperature (TLQ) of the slags.

Measuring and Modeling Viscosity of CaO-Al2O3-SiO2(-K2O) Melt

“…It can be observed that viscosities estimated by Nakamoto et al's model decrease monotonously with increasing content of K 2 O for all the three groups. Although both experimental findings [1,2] and the results of our model give a viscosity tendency of first increasing and then decreasing. The position of maximum viscosity is in the field of K 2 O/Al 2 O 3 > 1, whereas it is K 2 O/Al 2 O 3 = 1 for the current model.…”

“…In other words, the viscosity exhibits a maximum with the content of K 2 O, and the position of maximum is in the field of K 2 O/Al 2 O 3 > 1. The phenomenon that the viscosity increases with K 2 O content was also proved by the experimental results of Sukenaga et al [1] and Kim et al [2] However, the viscosity maximums are not found in their work for the high content of Al 2 O 3 .…”

“…It was found that viscosity decreases with increasing the additive content of Li 2 O or Na 2 O, whereas the tendency is opposed for K 2 O. [1] Kim et al [2] studied the viscosity variation of CaO-SiO 2 -Al 2 O 3 -MgO-K 2 O system with K 2 O, and the same conclusion was also found that adding K 2 O would increase viscosity. However, the interpretation to this phenomenon is still inexplicit.…”

Effect of Potassium Oxide Addition on Viscosity of Calcium Aluminosilicate Melts at 1673–1873 K

“…Similar phenomena have been observed by other researchers as well. [9][10][11] Recently, Zhang and Chou 11) examined the effects of K2O addition on the viscosity of CaOSiO2-Al2O3 melt for Al2O3 content of 2-10 mol%. They found viscosity of the 38.2CaO-59.8SiO2-2.0Al2O3 (mol%) melt increased with the K2O additon when K2O content was less than 3 mol%, but decreased with K2O content when K2O content > 3 mol%.…”

Application of Alkali Oxides in LF Refining Slag for Enhancing Inclusion Removal in C96V Saw Wire Steel

“…15,16) Thus, the change of slag structure with K 2 O seems to be determined by the dual balance of the following conditions: ① the modification of complex silicate structures to simpler dimers and monomers of [Si 2 O 7 ] 6 − , 5 − due to the ionic charge-compensating effect. According to a series of literatures [17][18][19] it is likely that the abovementioned effect of K 2 O on the aluminate structure is more dominant. Furthermore, according to Sohn I, 4) after treated by K 2 O, the Si-O-Al bonding within the slag increased, thus polymerizing the slag to form complex aluminates and aluminosilicate structures.…”