Abstract: Molten metal in an electric arc furnace is stirred by introducing a gas into the melt through tuyeres mounted in the hearth. Each tuyere has an inlet portion having a passage of relatively large diameter and an outlet portion having a passage of relatively small diameter. The tuyere is mounted in the bottom of the electric arc furnace with the inlet portion extending through the furnace shell and part of the refractory brickwork. With this design of tuyere gas at conveniently available pressure (16 bar A) can be fed to the tuyere and leaves the outlet portion at least at sonic velocity thus forming a relatively stable jet which inhibits molten metal entering the tuyere. The outlet portion may have a first portion with a slightly larger internal diameter than a second portion downstream of the first portion. When the second portion is fully eroded the flow of gas increases and triggers an alarm.

Abstract: An apparatus for shielding a stream of molten metal during teeming comprises a housing (106) and a ceramic ring (105). The ceramic ring (105) is made of compressible material and is tapered so that on insertion in the housing (106) it readily forms a seal with lips (107) and (113) which project inwardly from the outer wall (111) of the housing (106).