The viscosities of CaO-SiO 2 -10wt%MgO-20wt%Al 2 O 3 -Na 2 O slags (CaO/SiO 2 ¼ 0.8-1.2, wt%Na 2 O ¼ 0-10) were measured to estimate the effect of Na 2 O on the viscous behavior at elevated temperatures. The slag viscosity at 1773 K decreased with increasing Na 2 O contents, which is observed in a basic oxide component. However, the FT-IR spectroscopic analysis of the slag structure seemed to verify that [AlO 4 ]-tetrahedra depolymerized more readily than [SiO 4 ]-tetrahedra due to ionic charge compensation which has a tendency to be more effective on [AlO 4 ]-tetrahedra. Hence, for the present slag system, the viscosity decreased with additions of Na 2 O by providing network breaking O 2ions, and the charge balance by Na þ ions independently contributed to the depolymerization of the network structure of the molten slag. In addition, Na 2 O also lowered the critical temperature (T CR ) resulting in a larger temperature difference between the operating temperature (T OP ) and T CR , which can enhance operational stability.

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.

Breakup and spray formation by impinging liquid jets introduced into a low-speed cross-flow are experimentally investigated. Effects of the cross-flows on the macroscopic and microscopic spray parameters are optically measured in terms of jet Weber number and liquid-to-gas momentum ratio. The liquid stream undergoes Rayleigh jet breakup at lower jet Weber numbers and bag/plume breakup at higher momentum ratio through Kelvin-Helmholtz instability. In particular, the first and the second wind breakup occur at an intermediate jet Weber number. At higher jet Weber numbers, the hydrodynamic impact waves commands and the effect of the convective gas flows is insignificant. The breakup length rises in proportion to the jet Weber number, but starts to decrease when the jet Weber number further rises over 1000. The cross-flow promotes the jet breakup and renders a finer spray in an entire range of injection velocities.