The large octahedral crystals of spinel can precipitate from glass during the high-level waste vitrification process and potentially block the glass discharge riser of electrically heated ceramic melters. To help predict the settling behavior of spinel in the riser, the settling of single particles and agglomerates was studied in stagnant and transparent viscosity oils at room temperature with developed optical particle-dynamics-analyzer. Determined dimensions and terminal settling velocities of particles were used for calculation of their Stokes shape factors. Calculated shape factor for the glass beads was almost identical with the theoretical shape factor of 2/9 for a perfect sphere. The shape factor for single spinel crystal was about 7.6 % higher compare to the theoretically predicted value for octahedron. Stokes shape factor of irregularly shaped multi-particle agglomerates was lower than that of the glass beads and individual spinel crystals because of the higher surface drag caused by the larger surface area to volume ratio.
[1]
Abdelali Terfous,et al.
Measurement and modeling of the settling velocity of isometric particles
,
2008
.
[3]
P. Izák,et al.
Effect of feed melting, temperature history, and minor component addition on spinel crystallization in high-level waste glass
,
2001
.
[4]
D. Bickford,et al.
The Behavior and Effects of the Noble Metals in the DWPF Melter System
,
1997
.
[6]
Karel Svoboda,et al.
Free Settling of Nonspherical Particles
,
1994
.
[7]
N. K. Sinha,et al.
Drag on non-spherical particles: an evaluation of available methods
,
1999
.
[8]
John D. Vienna,et al.
Development of Crystal‐Tolerant Waste Glasses
,
2010
.