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| Structural behavior of F- in mould flux melt of CaO-SiO2-Al2O3-Na2O-CaF2 system |
| Qiang Gao1,2,Yi Min1,2,*,Cheng-jun Liu1,2,Mao-fa Jiang1,2 |
1 Key Laboratory for Ecological Metallurgy of Multimetallic Mineral Ministry of Education, Northeastern University, Shenyang 110819, Liaoning, China
2 School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China |
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Abstract The influence of fluorine on the structure of CaO-SiO2-Al2O3-Na2O-CaF2 continuous-casting-type slag was measured by Raman spectroscopy, and the degree of polymerization of mould flux and the structural behavior of F- in the melt were investigated by classifying and quantifying the structural species of F- ions. The results exhibit that the main structural units of Si-O tetrahedra are Q0, Q1 and Q2, and the actual measured number of non-bridging oxygen ions in the ��SiO4��-tetrahedra (denoted by NBO/T) increases from 2.73 to 3.44 with increasing the molar ratio of F to (F+O) (denoted by XF/X(F+O)) from 0.06 to 0.19. It means that the degree of polymerization of melt structure decreases with an increase in XF/X(F+O). In addition, most of F- ions were distributed in Si-O tetrahedra and Al-O tetrahedra. With increasing XF/X(F+O), the complex structural units Al-O tetrahedra are gradually replaced by discrete structural units AlF4- because of the breakage of Al-O bonds in Al-O tetrahedra by F- ions, and the Si-O (bridging oxygen) bonds of Si-O tetrahedra are broken to form ��SiOnF4-n��-tetrahedra by F- ions coordinating with Si4+.
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Received: 21 November 2016
Published: 01 December 2017
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2017, Vol. 24 
