Effects of particle size and briquetting of soda-lime-silicate glass batch on viscosity during batch-to-melt conversion

Abstract

To assess the effects of grain size and briquetting on glass-batch melting, we measured the viscosity (ηb) of an industrial glass batch during its conversion to molten simulated architectural glass within the temperature interval of 1050-1300°C and at a shear rate of 0.02 s−1. On the basis of the mass fraction of undissolved sand (xs), which was determined using X-ray diffraction analysis on quenched batch samples, and the gas-phase fraction (ϕp), which was obtained from volumetric measurements, we established the relationship ln(ηb/ηm) = a0 + bsxs + apϕp, where ηm is the transition melt viscosity, a0 is the melt homogeneity coefficient, bs is the coefficient for undissolved sand, and ap is the coefficient for bubbles. The obtained values, bs = 8.756 and ap = 0.658, indicate that undissolved silica sand strongly influences batch viscosity. Consequently, compared with coarse-grained batches, fine raw materials and briquetting resulted in lower batch viscosity during conversion. Owing to their lower viscosities and higher heat conductivities, batches from finer raw materials or batches shaped into briquettes are expected to enhance the melting rate of batch blankets in industrial glass-melting furnaces.