Regarding the fact that the new and modern electric arc furnaces in order to decrease the level of slag penetration in to the steel molten are equipped with the eccentric bottom tap-hole (EBT) or the bottom discharge mechanism, in such furnaces the discharge case is perpendicularly located at the furnace floor. To prevent the discharge system destruction and molten penetration during the fusion and refining stage in the furnace, at the time when the EBT is closed and before starting reloading, metallic charge of the molten discharge cavity is filled from the bottom with a type of sand like the olivine sand.
The EBT olivine sand is used as the electric arc furnace orifice sand which is discharged from the bottom.
This sand, through formation of a sintered and concentrated layer prevent penetration of molten to the next sand layers and finally at the time of value opening based on the static pressure caused by molten pressure this layer is broken from the sintered and the molten is discharged.