Fiscal year 1996 laboratory scale studies of the WVNS flowsheet for remediation of Tank 8D-1 and Tank 8D-2

These tests simulated the West Valley (WV) tank heel removal flowsheet in which oxalic acid solution (OAS) is used to elute Cs from zeolite in tank 8D-1 for 28 h. The eluent is then transferred to tank 8D-2, to dissolve the waste sludge heel. Sequence for the tests were: elute 10 g of Cs-loaded zeolite for 28 h at 50 C at 40 L/kg- zeolite, using 8 wt% OAS; decant used OAS and add 240 g waste slurry simulant, which was washed to <2g/L dissolved solids and containing 120-140 g total oxides/L; let the 3 test combinations (various Fe{sub 2}O{sub 3}) and control age at 50 C for 50 h; and after adjusting pH from 2.5 to 5, sampling at 0.25 to 16 h. Results include visual and analyses; data tables include compositions of the OAS after the Cs- zeolite contact, Cs eluted, supernate OAS in contact with sludge, and neutralized tests. Data have also been graphed for each element vs contact time. Cs elution data was consistent with >90% eluted; the OA conc. after Cs elution was also consistent with essentially no acid consumption. During contact with OAS at pH 2.5, the solution appears to have come into equilibrium with the sludge solid almost immediately; presence of additional Fe oxide appears to have decreased the Cr/Ni/Mn relative solubility. After neutralization, elements that form more insoluble hydroxides such as Fe, Ni, Mn, Ca, and Sr show lower conc. in supernatant; Si may also have been removed. Flowsheet testing confirms that OA is efficient for eluting Cs from zeolite and promotes dissolution of sludge heels in the WV tanks