GB1423236A - Process and device for the treatment of baths of molten metal - Google Patents

Abstract

1423236 Aerating and circulating liquids ACIERIES REUNIES DE BURBACH-EICHDUDELANGE SA 7 March 1973 [8 March 1972] 11104/73 Heading BIC [Also in Division C7] In treating a bath of molten metal, e.g. in a ladle 10, mixer or furnace, the metal is continuously circulated by vertical insertion therein of a device 2 comprising a lower tubular section 20, a separating and decanting section 22 comprising lateral openings 23, and an upper tubular section 24, and by blowing gas (e.g. inert, oxidising or reducing) upwardly through the device so that it mixes with the metal confined in the section 20 to form a reduced density emulsion which rises to the separating and decanting section where the gas escapes through the section 24 and the metal flows off through the openings 23 to return to the bath. The treatment may be desilication, desulphuration, dephosphorisation, deoxidation, adjustment of constituents, alloying, thermal or chemical homogenization, or degassing. The molten metal (e.g. pig iron or steel) may be treated or alloyed by introduction of additives (e.g. powders, granules, premelted products, consumable electrodes) through the section 24. with, as shown, the device 2 positioned so that the openings 23, in the form of downwardly sloping radial ducts, are immersed below a surface dross 12, by mixing with a reactive treatment slag with the device 2 positioned so that the openings 23 open into or on the slag, or by simple circulation. Where the openings 23. are to be immersed they may be initially closed, to prevent entry of dross, by consumable caps of sheet metal or cardboard. The gas may be introduced through an injector 21 incorporated in the device 2, through means such as porous bricks, or bundles of tubes in the body of the bath or the base of the bath receptacle, or through a lance co-axial of the device. The gas may be partially replaced by introducing, mechanically or pneumatically, within the column of rising metal, materials (e.g. carbonates) giving off gas by thermal decomposition. Powdery additives may be carried in suspension in the blown gas. The flow of metal through the device may be periodically varied by variation of gas flow. Each of the openings may comprise cylindrical or prismatic and/or frusto-conical or frusto-pryamidal ducts. The ratio of the cross-sectional areas of the sections 24, 20 may be between 3/1 and 1/1. The device 2 may be stationary or, if desired, rotated.