Abstract: A screw type, polymeric material extruder with an elongated body having a cylindrical bore with a hollow screw in the bore, the screw having external and internal threads. A cylindrical body is within the internal threads, and the screw with the wall of the bore and with the cylindrical body forms, respectively, an external material flow chamber and an internal material flow chamber. The cylindrical body can have channels for heating fluid and for additives or dyes. The screw can have openings for feeding one material to a single extrusion head with one mouth by way of both chambers, or the chambers can be supplied with the same or different materials which are fed by way of the chambers to an extrusion head with two mouths for applying the latter materials separately.

Abstract: A process for continuous treatment of hot metal topped from a blast furnace is disclosed. The process involves the steps of deslagging the metal, flowing the deslagged metal along a launders and blowing treatment agents in powdered form in a gas jet into the hot metal as it flows along the launder, the treatment agents being lime, fluorite, iron oxide or sodium carbonate.