Scrap iron preheating

Fig. 3.27. Scrap preheater with high-momentum flames driving through the interstices of iron scrap, to preheat it prior to big ladie melting, and to incinerate paint and oil on the scrap.

Ferrous foundries consist of two types steel foundries in which electric furnaces (EAF and induction) are used, and iron foundries in which hot-blast cupolas and/or electric furnaces are used. Electric furnaces use virtually 100% scrap charges. Cupolas are shaft furnaces which use preheated air, coke, fluxes, and metallic charges. Scrap is over 90% of the metallic charge. Cupolas accounted for about 64% of total iron foundry scrap consumption in 1994 and electric furnaces accounted for about 34%. The balance was consumed by other furnaces, such as air furnaces. Iron foundry products have a high carbon content and the scrap charge usually contains a high percentage of cast iron or is used in combination with pig iron. 

When the furnace is tilted toward the charging floor, which is on a platform above ground level, soHd scrap is dumped by an overhead crane into the mouth of the furnace. Scrap can form up to 30% of the charge unless it is preheated, when up to 45% may be used. The crane then moves away from the furnace and another crane carries a transfer ladle of molten pig iron to the furnace and pours the molten pig iron on top of the scrap. 

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