A gelation facility for the preparation of ceramic microspheres

Abstract

A gelation facility has been commissioned inside a ‘walk-in’ fume hood for producing oxide microspheres through internal gelation process. This facility would serve both as a test bed for optimizing the process parameters and would serve ‘as a prototype’ for the system to be incorporated in a remotely operated facility for the production of (U,Pu) mixed oxide microspheres containing minor actinides. This facility consists of an indigenously designed 1.6 m tall modular glass column with stainless steel modular support structure, oil reservoir with a recirculation pump, resistive heater, double-jacketed feed tank, a controlled pressure transfer facility, a nozzle with an electromagnetic vibrator, cooling stations for broth preparation, mesh belt conveyor, soft gelled spheres collection tray and microsphere washing stations. The design of the glass column has been optimized to avert choking due to aggregation of the microspheres. The latter has been accomplished by arriving at the optimal flow with the help of a simple flow model. This flow model considers the temperature dependence of viscosity and the temperature distribution within the column, experimentally determined by using infrared thermography. The optimal composition of the feed (broth) has been arrived at by using an innovative measurement of the viscosity of the sol and gel during gelation. The innovation in both equipment and method are being reported for the first time. A novel method to quantify the gelation characteristics of sol has been devised and is being reported for the first time.