Abstract: The invention relates to a process for automatically deslagging a cupola furnace and to an improved cupola furnace using this process.According to the invention the bottom of the crucible is permanently connected to atmosphere via a siphon sill whose level is determined so that the interface between pig iron and slag is sometimes above and sometimes below this sill. The side wall of the cupola furnace has on the one hand a taphole for the pig iron opening into the crucible level with the hearth and which can be sealed with a plug and on the other air blowing tuyeres in the upper part of the crucible, as well as a siphon linked with the crucible for the supply thereof by means of a passage whose lower edge is adjacent to the bottom of the crucible and whose upper sill extends below the maximum permitted pig iron level determined by the siphon outflow, whereby the maximum permitted slag level is located below the nozzles.

Abstract: An improved cupola furnace which comprises, in combination, on the one hand at least one tap hole for the pig iron opening into the crucible level with the hearth, a passage for evacuating the slag and air-blowing tuyeres, on the other hand, a storage tank closed by a cover and permanently communicating, near its bottom, via the tap hole, with the crucible, finally a removal siphon permanently communicating with the tank via an opening which opens near its bottom and with the outside via an overflow sill, at least one pneumatic device being connected to the upper part of the tank and enabling this latter to be selectively placed under two different pressures.