Structural behavior of F- in mould flux melt of CaO-SiO2-Al2O3-Na2O-CaF2 system

• 作 者: Qiang Gao Yi Min Cheng-jun Liu Mao-fa Jiang
• 机 构: Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education),Northeaste
• 出 处: Journal of Iron and Steel Research(International)
• 发表日期: 2017年11期
• 关键词: Mould flux F-ion Melt structure Polymerization degree

The influence of fluorine on the structure of CaO-SiO_2-Al_2O_3-Na_2O-CaF_2 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 Q~0,Q~1 and Q~2,and the actual measured number of non-bridging oxygen ions in the[SiO_4]-tetrahedra(denoted by NBO/T)increases from 2.73 to 3.44 with increasing the molar ratio of F to(F+O)(denoted by X_F/X_((F+O)) from 0.06 to 0.19.It means that the degree of polymerization of melt structure decreases with an increase in X_F/X_((F+O)).In addition,most of F-ions were distributed in Si-O tetrahedra and Al-O tetrahedra.With increasing X_F/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 SiO(bridging oxygen)bonds of Si-O tetrahedra are broken to form [SiO_nF_(4-n)]-tetrahedra by F-ions coordinating with Si~(4+).

The influence of fluorine on the structure of CaO-SiO_2-Al_2O_3-Na_2O-CaF_2 continuous-casting-type slag was measured by Raman spectroscopy, and the degree of polymerization of mold 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 Q ~ 0, Q ~ 1 and Q ~ 2, and the actual measured number of non-bridging oxygen ions in the The increase of [SiO 4] -tetrahedra (denoted by NBO / T) increases from 2.73 to 3.44 with increasing the molar ratio of F to (F + O) (denoted by X_F / X _ ((F + O)) from 0.06 to 0.19. that the degree of polymerization of melt structure decreases with an increase in X_F / X_ ((F + O)). In addition, most of F-ions were distributed in Si-O tetrahedra and Al-O tetrahedra.With increasing X_F / X_ ((F + O)), the complex structural units Al-O tetrahedra are still replaced by discrete structural units AlF4-because of the breakage of Al-O bonds in Al-O tetrahedra by F-ions, and the SiO (bridging oxygen) bonds of Si-O tetrahedra are broken to form [SiO_nF_ (4-n)] - tetrahedra by F-ions coordinating with Si ~ (4+).