2002 Volume 42 Issue 8 Pages 921-929
Dissolution of fluorine in secondary refining and synthetic CaO-SiO2-Al2O3(-P2O5) slags has been studied by using the shaking test and its behavior is discussed based on the results for the time dependence of Ca, Si, Al and F contents in aqueous solution. It was found that fluorine dissolution is affected by the contents of SiO2, F and total Fe in slag and particularly its effect is obvious in synthetic slags. The dissolved fluorine from slags with low contents of SiO2 and total Fe can be immobilized through the incorporation of fluorine into precipitated hydrates such as CaO-Al2O3-H2O compound and CaO-SiO2-Al2O3-H2O gel. In the case of slags with high SiO2 and low total Fe contents, the dissolved fluorine can be immobilized through the formation of CaO-SiO2-H2O-SO4-F gel by the addition of gypsum to aqueous solution. The dissolution behavior of fluorine in seawater has been also studied.
