Rheology of spinel sludge in molten glass

Spinel sludge, which forms while vitrifying high-level waste, obstructs the flow of molten glass and damages the melter The effectiveness of removing spinel sludge from a high-level waste glass melter depends on its rheologic al behavior We prepared spinel sludge in a laboratory crucible by allowing spinel to settle from molten glass and measured the response of the sludge to shear using a rotating spindle viscometer. The shear stress increased no nlinearly with the velocity gradient (the shear rate) and with rime at a co nstant velocity gradient, as is typical for a pseudoplastic rheopectic liqu id. The apparent viscosity of the sludge substantially increased when RuO2 needles were present.