Furnace refractory maintenance

The following methods are commonly practiced.

Slag splashing

Slag splashing is done in steelmaking vessels. After steel tapping, some amount of slag is retained. Composition of slag with respect to FeO and MgO is adjusted. FeO makes the slag adhesive on the lining and MgO makes the lining high temperature resistant. Nitrogen is blown from top to splash the slag. The splashed slag gets coated on the lining. To reduce excessive slag build up in the bottom, excess slag is then poured before charging.

In case of hybrid blowing practice formation of skull may result in a failure of the bottom stirring elements.

Slag coating and slag washing

The small amount of liquid slag is retained in the vessel after tapping. Slag is enriched with dolomite or raw dolomite to cool the slag and to increase its adhesive properties. Vessel is rocked several times to coat the bottom and bottom joint with a slag.

Hot patching 

Self flowing refractory mixtures enable precise maintenance of the scrap impact zone, tapping pad and bottom joint.

Gunning

By gunning, i.e. maintenance of pre- worn areas with special gunning mixtures, vessel lining life can be extended.

Flame gunning involves simultaneous melting of a refractory powder and gunning at the hot surface. Since the gunned repair material is dense and fused directly on the hot surface excellent results on life of lining is obtained in LD converter.