(315e) Understanding Melter Feed Rheology during Conversion to Glass: Effects of Foaming and Silica Dissolution

As nuclear-waste glass-melter feed (a slurry mixture of nuclear wastes with glass-forming and glass-modifying additives) is converted to molten glass in a continuous electrical glass-melting furnace, the feed becomes a continuous glass-forming melt where dissolving refractory constituents are suspended together with numerous gas bubbles. Knowledge of various physical properties of the reacting melter feed is essential to understand the feed-to-glass conversion during melting. We studied the melter feed viscosity during heating and correlated it with the volume fractions of dissolving quartz particles and gas phase. The measurements were performed with a rotating spindle rheometer on the melter feed heated at 5 K/min, starting at several different temperatures. The effects of undissolved quartz particles, gas bubbles, and compositional inhomogeneity on the melter feed viscosity were determined by fitting a linear relationship between the logarithm of viscosity and the volume fractions of suspended phases. The study would help to understand the effect of melter feed viscosity on mass and heat transfer within the cold cap, which will be an important part of a detailed mathematical cold cap model to predict the glass production rate of melter feeds.