Noble Metal Chemistry and Hydrogen Generation During Simulated DWPF Melter Feed Preparation

Catalytic Interactions of Rhodium, Ruthenium, and Mercury During Simulated DWPF CPC Processing With Hydrogen Generation

“…The early Rh peak has the potential to be the maximum SRAT hydrogen generation rate. 9 The data in the Rh-RuHg matrix study are consistent with this picture. The addition of Hg into the testing, however, had the largest impact on the initial hydrogen peak associated with Rh.…”

“…The bead-frit matching test with 0.2 wt% Ru and 1.5 wt% initial Hg had a very similar hydrogen generation rate profile to the two bead-frit tests with 0.2 wt% Ru and no Hg. 9 These data are not inconsistent with a weak Hg effect in the matrix data, since the initial Hg/Ru ratios were centered about 50 in the matrix study compared to 7.5 in the bead-frit matching test. The matrix study would tend to magnify any effect of Hg relative to the earlier bead-frit matching test because of the relatively higher Hg/Ru ratios.…”

“…Results from the first four runs (RhRuHg1, 2, 10, and 4) and last four runs (RhRuHg8, 11, 12, and 13) indicated high extents of dissolution for all three elements throughout reflux consistent with the steady low pH readings. Results for the middle four runs (RhRuHg5,6,7,and 9) showed about 55-65% as much Mg and Mn dissolution relative to the other runs. Data for RhRuHg6 and RhRuHg9 were compared to their replicates, RhRuHg13 and RhRuHg11 respectively, and the lower extents of dissolution were not confirmed indicating a high likelihood of analytical issues with the ICP-AES supernate samples from the middle four runs (twelve samples analyzed as one block).…”

DWPF Simulant CPC Studies for Sb7b

“…Generally the peak solubility period for the noble metals appeared to have already occurred by the end of acid addition consistent with earlier studies on noble metal chemistry during SRAT processing. 15 Rhodium was still fairly soluble at the end of formic acid addition. This is the period where a nitro-rhodium complex tends to be catalytically active for hydrogen generation.…”

“…The calculation methodology has been previously documented. 15 An internal standard flow is usually established with helium. Other gas flow rates are determined relative to helium by taking the ratio of the two gas volume percentages times the helium standard flow.…”