Allmanna Svenska Elektriska Aktiebolaget

Jan B:Son Uggla

Bengt Fredriksson

Magnus Gustav Tiberg

An unfinished steel melt is tapped from its primary melter into an upright ladle having one or more nozzles in its side above the level of the melt. The ladle is then tilted in the direction of the nozzle or nozzles so that it covers them, oxidizing gases, slag formers, alloying elements, etc., then being injected into the melt below its surface as a refining and finishing operation. The ladle has an inductive stirrer that tilts with the ladle and may be used when the ladle is upright or tilted. By tilting the ladle the top surface of the melt is increased in area with a consequent increase in the area of contact between the melt and the slag which, together with the fact that the refining and finishing materials are injected directly into the melt, while the melt may be inductively stirred at the same time, provides for rapid and thorough refining and, if desired, alloying. After refining and finishing, the melt is cast in the molds. Only the single ladle is required to receive the melt from the primary melter, to refine and finish the melt, and to transport the melt to the casting location.

Apparatus and method for refining a metal melt

Unrefined steel is refined by the use of a refining slag in a furnace having two pressure-tightly interconnected, pressure-tightly covered upper and lower hearths having channeltype inductors for heating and stirring steel melts in the hearths, the refining being effected in the upper hearth only and which is of relatively small capacity and has its inductor tilted to effect vigorous melt flow. The refining is continued, batch after batch, with each batch transferred to the lower hearth which is of substantially larger capacity and where the refined steel can be held at a temperature lower than required for its refining, to obtain a volume of refined steel adequate for steel plant casting purposes. Gas pressure in the lower hearth maintains the melt level in the upper hearth as required during the refining, this gas pressure being lowered to transfer each batch of refined steel to the larger lower hearth, and then being increased again for the next refining operation. Finally, for tapping the refined steel in the large lower hearth, the gas pressure is raised in the latter and the accumulated melt is forced through an appropriately positioned tap hole. The small capacity and tilted inductor of the upper hearth makes it possible to use the channel-type inductor for steel refinement with a reactive slag; the lower temperature required for holding the accumulated melt makes practical the use of the channel-type inductor in the case of the lower hearth of large enough capacity for steel plant casting.

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Vasteras, Sweden

Jan B:Son Uggla