Patent ID: 8163231

Claim:
An apparatus for tapping molten metal from below a molten electrolyte less dense than the molten metal, the molten metal and the molten electrolyte forming a boundary at an electrolyte/metal interface, the apparatus comprising: a pipe having a first end and a second end opposite the first end, the second end adapted for immersion into the molten metal, the pipe defining an internal bore extending along a length thereof between the first end and the second end, the internal bore for passage of molten metal therethrough, the pipe having an enlarged wall portion proximate the second end, the enlarged wall portion extending radially outwardly from the bore in at least one direction and extending axially away from the second end a predetermined distance, the pipe having a front wall portion proximate the second end, said front wall portion being opposite the enlarged wall portion, the front wall portion having a first wall thickness, the first wall thickness being defined from the internal bore to a leading edge, the enlarged wall portion having a second wall thickness greater than the first wall thickness, the second wall thickness being defined from the internal bore to a trailing edge and wherein the second wall thickness is greater than 1.5 times the first wall thickness, whereby during tapping the enlarged wall portion traverses the electrolyte/metal interface and defines an obstacle to limit entrainment of electrolyte into the pipe.