Precipitation behavior of platinum group metals from simulated high level liquid waste in sequential denitration process

The precipitation behavior of the platinum group metals from a simulated high level liquid waste (HLLW) was experimentally examined in a sequential denitration process with formic acid. The precipitation fractions of Ru, Rh and Pd were found to depend on pH of the denitrated solution. The precipitation fractions of Ru, and Rh increased linearly with pH of the denitrated solution and became more than 98% over pH 7, and almost all Pd was precipitated at pH around 2. Results showed that more than 98% of Rh and Pd and about 80% of Ru could be recovered as precipitates from HLLW, by means of the sequential denitration process. (author)