Effects of alternative natural silicates on the kinetics of batch‐to‐melt conversion for E‐Glass fiber

For the fiberglass industry making E‐Glass fiber products predominantly, reduction in glass batch melting energy can be achieved by using alternative raw materials that improve the kinetics of the batch‐to‐melt (B t M) conversion process. The present study evaluates the effects of the following five types of natural silicate minerals: kaolin (comprising low [<5 wt%] and high [>50 wt%] “free” quartz), pyrophyllite, anorthosite, and wollastonite, on the B t M conversion process using a reference commercial E‐Glass composition. The study used isothermal heat treatment of individual silicate minerals and batch samples containing them, infrared spectroscopy, powder x‐ray diffraction, and differential scanning calorimetry (DSC) to characterize the stages of the BtM conversion process in detail. Based on the results of this study, a simplified reaction scheme or mechanism is proposed to account for the effect of batch chemistry on the B t M kinetics, namely, “free SiO 2 ” + “free CaO” → CaSiO 3 controls the kinetics of the batch melting. Relative to the E‐Glass control batch made using kaolin, sand, and limestone, the DSC tests showed the benefits of using pyrophyllite (replacing kaolin and sand), anorthosite (replacing kaolin and some limestone), and wollastonite (replacing limestone) in lowering the B t M conversion energy (from room temperature [RT] to 1200°C) between 20% and 50%.