Abatement of CO₂ emissions by lowering hot metal ratio (HMR) in basic oxygen steelmaking (BOS) process

Abstract

One of the most effective ways to reduce carbon dioxide (CO2) emissions in the oxygen steelmaking process is to lower the hot metal ratio (HMR) in the basic oxygen furnace (BOF). However, if the HMR is lowered, the amount of oxygen blowing during decarburisation in the BOF converter increases due to a lack of heat source. This reduces the cleanliness of the molten steel because the end point oxygen content in the molten steel increases. Hence, we sought to ensure the molten steel quality even at a decreased HMR of about 10%p compared to the current level to reduce carbon emissions in BOF steelmaking. An appropriate amount of silicon in hot metal was suggested to maintain the lowered HMR. In addition, a process optimisation for solving dephosphorisation as well as tramp elements problem was proposed even if the scrap charge increased. As a result, CO2 emissions from steel mills decreased from 2.20 t-CO2/t-steel to 2.06 t-CO2/t-steel.