GB1469113A - Electroslag refining - Google Patents

Abstract

1469113 Electroslag refining; continuous casting; composite casting; introducing metal into moulds BRITISH STEEL CORP 23 Oct 1974 [23 Oct 1973] 49296/73 Heading B3F [Also in Division F4] Molten metal, e.g. from an electrically-heated furnace or holding vessel 1, is conveyed up an electromagnetic launder 2 at a rate varied to control the rate of entry into a mould 3, to pass in small quantities through molten slag 8 for refining before solidifying, e.g. to form a continuous casting (which may be hollow if a stationary or moving mandrel is used) to be withdrawn by rollers 11, or to form a cast surface on a steel work-roll, Fig. 6 (not shown); there is some contact with the slag in the mould before the metal enters the mould. The bulk of metal in the launder 2 remains stationary and with controlled increases of voltage small quantities are conveyed into the bath of slag 8. The time interval between pulses determines the amount of refining which occurs in the inlet channel 7 through the mould wall. Metal on the surface of the stream 13 in the launder 2 passes down into the vessel I while metal beneath ascends. An electrode 12 in the slag 8 and connected to an A.C. or D.C. supply may be water cooled and of copper or graphite to maintain the slag temperature or it may be consumable and of the metal for casting. The metal may pass up into a chamber 15, Fig. 3, through an opening 16 for stirring with slag (electromagnetically and/or by nitrogen or argon passed through ports in the chamber walls) before passing into the mould 3. Electrodes 12 may depend into the chamber 15 to heat the contents and those of the mould. A zirconium boride/silicon carbide metering throat may be fitted into the mould inlet 7 to determine the flow rate. The chamber 15 may be annular and surround a mould 3 which has a number of inlets 7. The metal is held in the chamber 15 for a few seconds before the level is raised to determine the flow rate into the mould. The slag in the chamber 15 may be of different composition or electrical conductivity.