Effect of adding semi-coke in blast furnace on droplet characteristics of charge column and coke solution loss

With the promotion of the "carbon peaking and carbon neutrality" policy, steel enterprises are facing the pressure of ultra-low carbon emissions, and reducing coke consumption is one of the essential measures to achieve low carbon smelting in blast furnaces. Semi-coke has similar physical and chemical properties to coke and can meet the basic needs of blast furnace ironmaking, which can be used as a substitute for coke. The droplet characteristics and solution loss degree of coke after adding semi-coke were studied under simulated blast furnace conditions. Then the feasibility of replacing coke with semi-coke in blast furnace ironmaking was discussed. The results show that the droplet characteristic is better in mixed coke than in unmixed coke. When the proportion of semi-coke added decreases from 30% to 10%, the droplet characteristic value S decreases from 774 kPa·℃ to 597 kPa·℃, the max differential pressure ΔPMAX decreases from 13.66 kPa to 11.79 kPa, and the softening zone becomes more comprehensive and the position descends. The zone of melting widens and decreases, while the range and position of the soft melt zone are gradually close to the situation of mixed coke loading, and the permeability of the charge column is good. After adding semi-coke, the slag phase is more stable and the reduction degree of Fe is higher. Adding semi-coke can reduce the porosity of coke to a certain extent, reduce the coke solution loss degree, provide good protection for coke, and improve the permeability of the charge column. It proves that it is feasible to replace metallurgical coke with semi-coke, providing theoretical basis and technical guidance for using semi-coke in blast furnaces.