Small to Full-Height Scale Comparisons of Cesium Ion Exchange Performance with Crystalline Silicotitanate

Abstract

ABSTRACT Crystalline silicotitanate (CST) ion exchanger is planned for use in the removal of cesium (137Cs) from the aqueous phase of Hanford tank wastes in preparation for vitrification at the Waste Treatment and Immobilization Plant (WTP). Batch contact testing was conducted to assess cesium exchange kinetics at four different CST particle-size distributions. Column testing was conducted at three column sizes, small (2.5% full height), medium (12% full height), and full height, to assess Cs loading performance behavior. Testing at the small scale was compared to actual Hanford tank waste testing to verify the validity of simulant tests to reflect full-height column performance. CST particle size adjustment was essential in scaling the column dynamics down from full scale to medium and small scales. The mean (d 50) CST particle size needed to be reduced from 633 microns to 567 and 542 microns, respectively, to achieve appropriately scaled results. Based on these results, a determination of intraparticle and film-diffusion impacts on overall mass-transfer coefficients will allow future modeling of the breakthrough performance at a range of process conditions.