Volatilization Of Fluoride Slag In Electroslag Remelting And Its Effect On Slag Properties

The fluorine content of slag in Electroslag Metallurgy directly determines its physicochemical properties under high temperature.Fluorine slag in the electroslag has the phenomenon of weightlessness at high temperature,and traditional physicochemical properties measurement of electroslag is generally carried out at high temperature through a long time.So the slag composition will change during the measurement of the high temperature properties.The volatilization mechanism of fluorine slag is still lack of the systematic effect under high temperature Therefore,it is of great significance to study the volatilization mechanism of fluorine slag in electroslag and its influence on the determination of high temperature properties.Based on relevant research achievements on the physicochemical properties of fluorine slag and the volatilization of fluorine slag in Electroslag Metallurgy and the fluorine slag composition in industrial application,the experimental composition of the fluorine slag was established by the orthogonal experiment.The basic physicochemical and volatilization reactions of the medium fluorine slag were studied by Fact Sage software.Connecting with experimental measurements which include melting point,viscosity,thermogravimetric analysis and phase composition,the volatilization of fluorine slag was studied further.The modified composition of fluorine slag was obtained by volatilization mechanism,thermogravimetric experiment and theoretical calculation of medium fluorine slag.And the corresponding relationship between the corrected melting point,viscosity and composition is obtained.Finally,the difference of melting point of fluorine slag with the same ingredients between traditional industry and the slags prepared by chemical reagent was studied,and the uncertainty in the determination of the properties of the medium fluorine slag was discussed.The main conclusions are as follows:（1）Fluoride volatility from strong to weak in sequence of CaF₂>MgF₂>AlF₃>Si F₄>Al OF.The main fluoride volatilization is CaF₂,and a small amount of MgF₂ and a small amount of AlF₃.With the increase of the alkalinity of the fluorine slag,the fluorides volatilization can be suppressed.（2）The regression equations between theoretical melting point,viscosity and composition were obtained,and the melting point and viscosity of the related slag are measured experimentally.The result shows that the difference of the melting point is in the range of 123.19²56.87℃.The viscosity difference is in the range of 0.002⁰.104Pa·S^-1.（3）In the selected slag composition range,the slag weight loss of the slag in the melting point determination process can reach 3.37%¹5.13%.The volatilization kinetic equation and the corresponding relation between the volatilization weight loss and the composition are obtained;（4）According to the effect of volatilization mechanism and volatilization on the composition change of medium fluorine slag,a new method was proposed by the research group,the slag composition is revised and the regression analysis is carried out according to the modified slag composition.The regression equation between the actual melting point and the composition is obtained.（5）Through theoretical analysis and measurement,the influence of the change of the slag composition on the phase change is obtained.The research results can provide support for obtaining more accurate melting point and viscosity parameters of fluorine slag,and provide reference for the performance measurement of volatile slag.