The Effects of Silicic Acid, Aluminate Ion Activity And Hydrosilicate Gel Development on the Dissolution Rate of a Simulated British Magnox Waste Glass

Abstract

AbstractThe dissolution rate of a simulated Magnox waste glass has been investigated in single-pass flow-through experiments designed to investigate the role of Al and Si in the dissolution process. The results indicate that both Al and Si species suppress the rate of dissolution. These effects may be modelled using a combined Al/Si affinity term in a conventional glass dissolution rate law. Aluminium species may also play an inhibitory role when present at relatively high solution activities. In Si-rich alkaline media, the concentration of aluminium is controlled to very low levels by the development of secondary aluminosilicate phases. Removal of Al by secondary phase precipitation results in dissolved Al activities below that required to reach ‘saturation’ with respect to the glass.