In vitro dissolution of uranium mill products by the batch replacement method

Sixteen post-calcination uranium concentrate samples from two Australian uranium mills were analysed using the batch replacement method of Dennis et al. The samples were selected to represent a range of sulphate content. Results indicate that the degree of in vitro dissolution varies between samples and between solvents, and that the proportion of the most soluble fraction is linearly related to the sulphate content of the material. Results using de-ionized water, physiological saline and a simulated lung fluid indicate that, following initial release of the soluble fraction, the extent and range of in vitro dissolution of the remaining material is comparable to values reported in the literature. Close examination of the results indicate, however, that the fraction of uranium released cannot be satisfactorily interpreted using a time-dependent exponential and test appears to confirm this. Consequently, in vitro experimentation by the batch replacement method is considered to be of questionable value in prediction of in vitro behaviour in terms of dissolution half-times. 14 refs., 6 tabs., 6 figs