Effect of B2O3 on Melting Temperature, Viscosity and Desulfurization Capacity of CaO–based Refining Flux

Fluorite is widely employed as fluxing agent in metallurgy flux, which inevitably leads to serious fluorine pollution. In this work, B2O3 is used as fluxing agent of CaO–based refining flux to substitute for CaF2 so as to decrease the melting temperature and to improve the speed of slag forming and...

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Bibliographic Details
Published in:ISIJ International 2011, Vol.51(5), pp.702-706
Main Authors: Wang, Hongming, Zhang, Tingwang, Zhu, Hua, Li, Guirong, Yan, Yongqi, Wang, Jianhua
Format: Article
Language:English
Subjects:
Applied sciences
boron oxide
CaO–based refining flux
desulfurization capacity
Exact sciences and technology
Fluoride-free
melting temperature
Metals. Metallurgy
viscosity
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Summary:Fluorite is widely employed as fluxing agent in metallurgy flux, which inevitably leads to serious fluorine pollution. In this work, B2O3 is used as fluxing agent of CaO–based refining flux to substitute for CaF2 so as to decrease the melting temperature and to improve the speed of slag forming and the refining efficiency. The effects of B2O3 on the melting temperature, viscosity and desulfurization capacity of CaO–based refining flux were investigated. The results indicate that the fluxing action of B2O3 is better than that of CaF2 and Al2O3. For the high basicity CaO–based refining flux (mass ratio of CaO/SiO2 is 5.0–8.75), when CaF2 is substituted with B2O3, the melting temperature can be decreased remarkably. Especially, when the mass ratios of CaO/Al2O3 and CaO/SiO2 are in range of 1.1–4.0 and 5.25–8.0, respectively, the flux melting temperature is lower than 1300°C. At the same time, the temperature range, in which the flux viscosity is low, is expanded as well as the stability of flux viscosity varying with temperature is improved obviously. These variations of flux properties are favorable for refining process. The results of experiments on sulphur partition equilibrium between metal and flux indicate that the desulfurization capacity of flux can be improved markedly when CaF2 is substituted with equal mass of B2O3. When 4 mass% B2O3 is employed as fluxing agent and the mass ratio of CaO/Al2O3 is in the range of 1.5–7.0, the final sulfur content of metal can be controlled lower than 0.004%.
ISSN:0915-1559
1347-5460
DOI:10.2355/isijinternational.51.702