A Bench-Scale Natural-Recirculation Dissolver

A natural-recirculation dissolver closely approaching a stirred-tank reactor in behavior was developed, and its feasibility was demonstrated in the mercury-catalyzed dissolution of aluminum in nitric acid, It was designed to utilize the heat of reaction and evolution of gaseous reaction products for recirculation and mixing. The dissolvent was 5-molar nitric acid, containing mercury in concentrations from 10/sup -4/ to 10/sup -3/ molar as a catalyst. Dissolution rates for 1/7 scale, simulated MTR fuel elements of 2-S aluminum ranged from 0.25 to 4.0 mg/(cm/sup 2/)(rain), depending on the catalyst concentration in the dissolvent and the dissolvent flow rate. For comparable catalyst and acid feed concentrations, dissolution rates, based on unit net superficial velocities, were nearly 25 times those for dissolution of randomly- packed flat plates in a pilot plant, continuous, flooded dissolver. (auth