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Figure 10:
Reacted charge found in: a) Elkem Thamshavn, b) and c) Wacker furnace no.1.
Figure 11:
Loose SiC with quartz and slag found in Wacker furnace no. 4.
The main common zone for all three furnaces is about 1-1.5 m thick inactive zone
located around the furnace wall. Slag deposited from the bottom lining to the very top
of the furnace. In the bottom, layer consist mostly of green slag. Upwards, mixture of
slag and some quartz particle was found. Photo of slag deposition inside the furnace
and its scanning electron microscope image (SEM) is presented in the figure 12.
Figure 12. Slag deposition inside the furnace (Wacker no. 4) and its SEM image.
SiC crust found in Elkem Thamshavn was filling up almost half of the interior of the
furnace, from the bottom up to the top. There are large gas channels in the size of 5-
10 cm, as can be seen in figure13. The figure show two large pieces removed. The gas
channels were also seen in the previous FeSi excavation in Finfjord. Formation of SiC
crust was aslo observed during Wacker excavations. In both cases, it was found on the
outside of the electrode track zone in the height close to the electrode tip.
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