Non-isothermal Analysis on the Evaporation Behavior of CaF2-SiO2-CaO System Slag
CaF2-SiO2-CaO渣系的非等温挥发行为

The weight loss rate of CaF2-SiO2-CaO system was measured by a simultaneous thermal analyzer and platinic crucible at the heating rate of 10 K/min,and the thermal volatile kinetics studied using a non-isothermal approach.The conversion function f(α) and volatile kinetic parameters of slag were determined by the TG curves,kinetics model established verified,and its evaporation mechanism analyzed.The results indicated that the weight loss rate was closely related to the liquidus and phase of slag.But the volatility had no significant correlation with basicity.The evaporation causing the change composition of slag could be divided into two stages in 1373～1573 and 1573～1773 K.The former belonged to three-dimensional diffusion with differential form f(α)=3/2(1-α)4/3(1-α)-1/3-1]-1,the latter to random nucleation and growth with differential form f(α)=1/4(1-α)-ln(11-α)]-3.For the 70% CaF2-30% SiO2 slag system,the activation energy at two stages was 550.10 and 376.16 kJ/mol,and the frequency factor lgA 16.55 and 8.4,respectively.The experimental results were in good agreement with the kinetic model.