Numerical investigation of scrap charging into an ironmaking blast furnace

Steel industry consumes massive energy and generates a considerable amount of carbon dioxide, of which a major portion is taken by the blast furnace as it uses huge quantities of carbonaceous fuel materials. Charging of scrap into the blast furnace is considered to be a promising solution. In practice, the hot blast rate plays an important role in affecting the blast furnace performance. However, thus far, a systematic study with respect to the coupling effects of scrap charging and hot blat rate is not yet available. Also, the relationship between the scrap charging ratio, the hot blast rate and the key performance indicator largely remains implicit, which hinders the effective production and efficient use of the scrap. In this work, modelling of the blast furnace process with scrap charging is carried out using a previously developed continuum-based model. The effects of scrap charging amount and its interplay with the hot blast rate have been studied, which are analyzed in details with respect to the multiphase flow as well as the thermochemical behaviors. The simulation results show that the blast furnace performance is improved with an increased scrap charging ratio, in view of the increased productivity, decreased carbon input, energy input and carbon dioxide emission. Importantly, the utilization of scrap charging is more effective for the reduction of carbon input and energy input, and for the enhancement of productivity at a higher hot blast rate. However, the reduction of carbon dioxide emission with scrap charging is less pronounced at a higher hot blast rate since the top gas utilization factor is lower. The findings from this work should be useful to guide the production of blast furnace ironmaking process with scrap charging, helping to reduce the energy consumption and cut the carbon dioxide emission from the steel sector.