Abstract: The technical pathway of scrap steel into ladle during the LF refining process within long-process steelmaking to reduce hot metal consumption and its impact on the steelmaking process were studied. The results show that increasing the amount of scrap steel added to 150 kg/t can reduce the consumption of hot metal by 10% to 15%, while decreasing CO₂ emissions per ton of steel by 11.0%. However, the addition of scrap steel also brings a series of challenges. For every 50 kg/t increase in scrap steel, the nitrogen mass fraction of the molten steel increases by (3～5)×10^-6, and the total oxygen and hydrogen content also increase synchronously. The number and rating of inclusions in molten steel also increase，and power, electrode, and ladle refractory consumption significantly rise. Through thermodynamic and kinetic studies on scrap steel melting, quality standards of scrap steel for LF were established, and a method of preheating to 500～1 000 ℃ was proposed. By combining the improvement of heating efficiency, control of scrap steel particle size, and strengthening argon stirring, the melting time of scrap steel was shortened and the fluctuation of composition was reduced, the better economic and social benefits had achieved. Based on the synergistic improvement of calcium treatment and soft blowing process, the morphology and distribution of inclusions was improved, the purity of molten steel was enhanced, and the mechanical properties of steel had not been affected.

Key words: addition amount of scrap steel, LF, consumption of hot metal, carbon emission, scrap steel melting, inclusions