Abstract: A cupola furnace has a hearth 1 with tuyeres 2, a floor 3 and a tapping duct 4 leading to a forehearth 5. To enable treatment agents to be introduced into the melt in the furnace below the surface of the melt, the furnace is additionally provided with a lance 17 which extends through lining brickwork of the furnace into a sump 15 in the floor of the furnace. The lance 17 may be connected to a hot blast ring main which supplies the tuyeres 2.

Abstract: A hot-blast cupola furnace 1 has an inclined bottom 3 leading directly to a tapping conduit 4. The conduit 4 leads to a forehearth 5 having an iron discharge siphon 13, 14, 15 and two slag discharge siphons 16, 17. The forehearth 5 has an upper slag-holding part 10 and a lower iron-holding part 11, which also contains slag in its upper part down to the level of the tops of the siphons 16, 17. The part 10 is of greater horizontal cross-sectional area than the part 11. In this way the height of the slag column through which the iron passes in the forehearth is reduced and so is the area of the boundary layer in the forehearth. This causes the reaction between the iron and the slag to take place predominantly in the main furnace zone above the bottom 3 and not in the forehearth and in this way the life of the lining of the forehearth, which is a limiting factor on the possible continuous period of operation of the furnace, is prolonged.