Thermodynamic Analysis of Slag Recycling Using a Slag Regenerator

A waste-free steelmaking process, in which slags are recycled inside the steelmaking process itself by using a so-called slag regenerator, has been proposed, and its possibility was investigated by means of computer simulations.There are two kinds of discharged slags from the proposed process. One from the desiliconization furnace and another from the final dephosphorization furnace. The former slag would have no problem to be returned to a blast furnace or to a sintering process due to its low phosphorus content, while the latter could be used as fertilizer materials for its high phosphorus content such as 10 mass%.In a case that the blast furnace hot metal was of a composition of 5.04%C-0.12%P-0.50%Si-0.30%Mn on mass% base and half of the regenerated slag was recycled to the desiliconization furnace, the [P] level in the steel could be as low as 0.0087 and the total lime consumption for the whole process was approximately 20 kg/t HM. This lime consumption was about 1/2 of that in some conventional converter refining processes.