Process and apparatus for adding calcium to a bath of molten ferrous material.

摘要

A process for adding calcium to a bath (2) of molten ferrous material is disclosed in which a calcium metal-containing wire (1) is fed through a refractory lance (5) into the bath (2). Recirculatory stirring of the molten ferrous material is accomplished with an inert gas flow through the lance (5). The caicium-containing wire (1) is fed at such a rate that it substantially bends towards the horizontal direction after it leaves the lance (5) and melting of the calcium in the wire (1) occurs primarily in or directly below a region of downwelling of the molten ferrous material. Suitable wire feeding rates will depend upon the disposition of the lance (5) in the bath and the composition (e.g. clad or unclad) and cross-sectional dimensions of the calcium metal-containing wire (1). A preferred apparatus for adding processing elements in wire form directly into a molten material comprises a heat resistant nozzle (60) positionable relative to the surface of the molten material such that an inlet is disposed above the surface and an outlet (84) is disposed beneath the surface; a mechanism (24) for feeding the wire (20) through the nozzle (60) directly into the molten material; and a system (31, 33, 42) for injecting a substantially inert gaseous medium into the molten material together with the wire (20), whereby the inert gas substantially prevents closure of the nozzle (60) by solidified molten material and promotes mixture of the processing elements with the molten material through gas bubble agitation. The apparatus further comprises a substantially gas-tight conduit (44) connected to the nozzle inlet, through which the wire (20) and the inert gaseous medium are delivered to the nozzle (60). A pressure-driven seal (30) prevents atmospheric contamination and prevents loss of inert gas. Passing the wire (20) and gaseous medium through a bore in the nozzle (60) having an elongated, gradually tapered funnel-shaped section (80) adjacent the outlet (84) maximizes the effect of the inert gaseous medium.