A phenomenon occurring when melting zinc-coated sheets that cannot be avoided during melting processes in induction furnaces.
Zinc melts at 419.51°C and boils at 907°C. The resulting zinc vapors can diffuse into the refractory lining of the furnace and erode the coil windings. Therefore, the zinc vapor emerging from the melt must be captured and filtered out through suitable suction devices.
Humidifying the zinc oxide dust with water in a special granulating mixer results in a dust-free bulk granulate which can be transported in open containers and is accepted by recycling companies.
The negative effects on the durability of acidic crucibles can be reduced to an acceptable degree by taking suitable measures. When operated as follows, the service life of a crucible should not be significantly lower than that of crucibles used for melting zinc-free sheets: the sintering batch and the entire 2nd and 3rd batches are smelted from zinc-free scrap metal. From the 4th batch, scrap metal containing zinc can be added. Following downtimes, the 1st batch is smelted from zinc-free scrap metal. In addition, by sufficiently cooling of the furnace wall, zinc oxide diffusion through the refractory material can be reduced to such an extent that damage to the coils is excluded.