The effect of TiO₂ on the thermal stability and structure of high acidity slag for mineral wool production

In order to promote the application of Ti-bearing blast furnace slag in mineral wool manufacture, the viscosity, thermal stability and structure of melt were studied in this paper. And the concept of “Extreme Heat Release of Slag (EHRS)” was firstly proposed to quantify the thermal stability of melt. The results showed that slag viscosity decreased with the increase of TiO₂ content in the range of 0wt% to 6wt% at acidity coefficient (Mk) of 1.0~1.6. TiO₂ reduced the heat capacity of melt, but increased the EHRS. And when the Mk was 1.3, the EHRS was relatively large. The variation of activation energy of viscous flow had a good agreement with that of viscosity. In addition, TiO₂ acted as network modifier in the melts, which decreased the average number of bridging oxygens from 2.93 to 2.71. Ti⁴⁺ mainly existed in the form of [TiO₄] ^4– monomers and O–Ti–O in chain or sheet units, resulting in the decrement of slag stability. At the Mk of 1.3, increasing TiO₂ content to 6wt% would beneficial for the production of fibers with uniform diameter and length.