Dissolution of Sr precipitated with platinum group metals at the precipitation step by denitration in the 4-group partitioning process

Fujiwara, Takeshi; Morita, Yasuji  

The precipitation method by denitration with formic acid is adopted in the 4-Group Partitioning Process for recovery of Tc and platinum group metals (PGM) from high-level liquid waste. A part of Sr and some other elements are precipitated with Tc and PGM at the precipitation step by denitration. As Sr is one of the target elements of the 4-Group Partitioning Process, it is necessary to recover the precipitated Sr from Tc and PGM fraction. The present study deals with the process for dissolving the precipitate of Tc and PGM at the precipitation step to recover the precipitated Sr from Tc and PGM fraction. It was possible to dissolve the precipitated Sr thoroughly by 0.010 mol/dm nitric acid without dissolving PGM precipitate. Ba and Ni were contained in dissolved Sr solution. Any Sr was not appeared in the dissolved solution of PGM precipitate which remained after the Sr dissolution by 0.010 mol/dm nitric acid. The pH of the dissolved Sr solution was about 2. As the appropriate pH is 5 or higher to adsorb Sr on inorganic ion exchangers, it is demanded to adjust the pH of dissolved Sr solution for next treatment. Precipitation of Sr did not occur during adjusting the pH of dissolved Sr solution to neutral region with sodium hydroxide solution.