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Effect of MgO content on wetting and corrosion behaviour of corundum substrate by CaO–SiO2–MgO (−15%Al2O3) molten slags was investigated at 1450°C via joint application of a sessile drop technique, SEM–EDS detection and FactSage thermodynamic software. All slags exhibit good wettability on the substrate, and the contact angle values are small. Increasing MgO content from 7% to 9% in CaO-SiO2-MgO slags can increase the contact angle between the droplet and the substrate, while the substrate dissolution thickness and the slag penetration depth tend to decrease. Increasing MgO content from 8% to 15% in CaO-SiO2-MgO-15% Al2O3 slags can also increase the contact angle, but significantly decrease the slag penetration depth. The indirect dissolution thickness increases instead due to the formation of a large amount of MgAl2O4 by the interface reaction. The wettability can give an indication of the slag penetration depth in the substrate but not the dissolution thickness of the substrate. [ABSTRACT FROM AUTHOR]

The viscosity of steel slag plays an important role in mass transfer, steel-slag reaction rate and slag discharge. The viscosity of CaO–SiO2–FeOt–(Al2O3)–BaO slag with different Al2O3 content was measured. The effect of Al2O3 on structure evolution was investigated. The results showed that the viscosity of steel slag increased by the addition of Al2O3. The FTIR and Raman analysis all showed that the structures of [SiO4] symmetric tetrahedron and [AlO4] asymmetric tetrahedron were more complex by the addition of Al2O3. The XPS analysis the showed that the overall relative fraction of O0 increased from 34.72% to 38.05%, O- decreased from 55.55% to 54.07%, and O2- decreased from 9.73% to 7.88% with the Al2O3 content from 0% to 6wt%. The above analysis meant the degree of polymerization (DOP) increased by the addition of Al2O3, which are agree well with the results of viscosity measurement. [ABSTRACT FROM AUTHOR]

The viscosity of steel slag has an important influence on phosphorus mass transfer in dephosphorization process and slagging-off after dephosphorization. In current work, the viscosity of steel slag was measured and the influence of BaO on viscosity and structure evolution of steel slag was studied. The results showed that the viscosity of steel slag decreased with the addition of BaO. The Fourier transform infrared spectroscopy (FTIR) analysis showed that the degree of polymerisation (DOP) of steel slag is reduced by the addition of BaO. The Raman spectra quantitative analysis revealed that the convertion of Q² and Q³ to Q0 and Q¹ was promoted by the addition of BaO. The X-ray photoelectron spectroscopy (XPS) analysis indicated that the general relative fraction quantity of O0 decreased and that of O2- increased with the addition of BaO. The above analysis are agree well with the results of viscosity measurement. [ABSTRACT FROM AUTHOR]

This research aims to investigate the influence of the slag basicity from 1.40 to 1.83 on dephosphorization of the hot metal with a CaO–FeO–SiO2–MgO–Al2O3 molten slag at the low temperature of 1653 K. The results indicated that the dephosphorization ratio was increased with the increase of basicity. Even at the low basicities of 1.73 and 1.83, the dephosphorization ratios can be as high as 77.3 and 80.7%, respectively. With the increase of basicity, the contents of P2O5 and total iron in the slag were increased, whereas the content of MnO was decreased. The distribution ratio of phosphorus (L P) was expressed as log ⁡ L P = 19.4 Λ − 6381 T + 5.244 + log ⁡ f P + 5 4 log ⁡ P ( O 2) . The L P values calculated by the present method are well consistent with the measurement values. Besides, the dark grey phase B and the light grey phase D could be considered as the phosphorus-rich phases containing C2S solid particles. [ABSTRACT FROM AUTHOR]

The dissolution of three doloma based refractories in liquid CaO–Al2O3–SiO2–MgO slag was studied. Cylindrical refractory specimens of doloma, carbon bonded doloma, and magnesia doloma were rotated in a stationary crucible of molten slag under forced convection conditions. Slag composition, temperature, rod rotation speed and rod immersion time were varied. The refractory dissolution rate was determined from the change in diameter of the cylindrical specimens. The corrosion rate was found to increase with temperature and rod rotation speed and decrease when the slag was nearly saturated with MgO. The findings of the study substantiate the assumption that the diffusion of magnesium oxide through the slag boundary layer controls the corrosion process. The results indicated the overall corrosion process to be the dissolution of refractory material into the slag, followed by slag penetration of the pores and grain boundaries and finally, dispersion of the grains into the slag. [ABSTRACT FROM AUTHOR]