Answer:

The presence of Zn in the demolition is associated with its presence in the used load and with the incorrect melting of the same one in the furnace of induction.

The Zn volatilizes at 919ºC going from solid form (of galvanic sheets) to gas. In gas form it penetrates in the pores of the lining and having found its isotherm of solidification at 419ºC solid form happens again.

 

What can happen?

If coils are in poor condition Zn can be responsible for arches between turns

 

What to do?

1- Improve the densification of the lining

2- Proceed to change the way of providing the metallic load. The galvanized package should be introduced once the furnace has enough metal and temperature.