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Summary

FOSCAST RH and CAS-OB bells are monolithic pre-cast snorkels for use in the RH Degasser and casob ladle steel refining processes

Description

FOSCAST RH and CAS-OB bells are designed in two parts: the lower bell, which is replaceable, and the upper bell, which is reuseable. FOSCAST refractory castables with their superior properties are used to cover the complex reinforcement system used in the construction of the lower bell, to ensure complete bonding and a crack-free finish.

Application

The two parts of the bell are connected to one another in such a way that they can be easily detached and re-assembled, either by means of specially designed closure latches or welds. The lower bell is a steel framework which is cast in FOSCAST low cement castable refractory cement and manufactured by Foseco offsite, for delivery and assembly to the upper reuseable bell at the treatment station. This method of construction has largely replaced the mag-chrome brick structure for environmental and plant safety reasons. Double the life of the lower bell has been achieved using the FOSCAST RH and CAS-OB bells.

Function

The FOSCAST CAS-OB bell is a single snorkel which is immersed into the steel in the refining ladle to enable alloying and slag forming materials to be added to the ladle in a sealed environment under a controlled atmosphere. FOSCAST RH degasser snorkels consist of two refractory tubes which are immersed into the steel in the refining ladle in a similar way to the casob, except that the steel is drawn up into an evacuated chamber above the snorkels. Argon is blown into one tube, which makes the molten steel column \"lighter\" than that in the other tube, enabling the steel to flow continuously between vessel and ladle. The argon gas also contributes to the removal of hydrogen and nitrogen.

Benefits

	Improvement of RH and CAS-OB bell life.
	High resistance to abrasion.
	High resistance to temperature changes.
	Ease of replacement.