PREHEATING OF A STEEL LADLE VIA A DC PLASMA TORCH: PRELIMINARY RESULTS ON ECOLOGICAL IMPACTS IN THE COMPARISON WITH A NATURAL GAS BURNER

This paper is placed in the general context of European industrial research aimed at the de-carbonization of energy intensive productive processes, specifically in the sector of secondary steelmaking. It synthesizes the main ecological findings of the project “PlasmaPilot” (acronym for “Flexible Ladle Preheating Procedures using Plasma Heated Refractory”), financed by the European Commission and ended in December 2023. The main goal has concerned investigating on the feasibility of substituting the current and traditional equipment used for steel ladle preheating, based on gas burners of fossil origin gases, mostly natural gas (NG) and, to a limited extent, Liquid Petroleum Gas (LPG), with an electrically supplied plasma torch. In steelmaking, ladles are used to transport liquid steel from tapping at Basic Oxygen Furnace (BOF) or Electric Arc Furnace (EAF) to teeming at caster. Ladle preheating is a crucial procedure undertaken on a cyclic basis, each time a ladle, after maintenance stops or after refractory relinings, has to return to operational service and be filled with hot liquid steel. The preheating procedure is finalized to minimize thermal shock and damage to the refractory lining and to reduce the temperature drop of the liquid steel. A plasma preheater, in particular in the form of a non-transferred arc DC plasma torch, has been selected as the most promising solution to fulfil this technological requirement because of higher attainable temperatures and, compared to a gas burner, potential improvements in flexibility, process control and safety. This paper focuses on the ecological impact assessment in the use phase, showing that results and potential ecological advantages depend on the electricity mix composition considered, whereas more updated data regarding the NG supply chain may be needed.