REFRACTORY LANCE ASSEMBLY AND REFRACTORY LANCE TUBE

Described are various embodiments of a refractory lance assembly and a composite refractory lance. In one embodiment, a refractory lance assembly is provided that comprises: an immersion tube having an immersion tip immersible within a melt and an extension tube coupled at an opposed end thereof to form a longitudinally extended composite tube therewith defining an optical path therein, wherein said longitudinally extended composite tube is injectable, in use. with an inert gas to form and probe an immersed melt surface. The assembly further comprises a shroud longitudinally encasing the composite tube and injectable with inert gas to mitigate fluid contamination of the composite tube and immersed melt surface.