Abstract: Under conditions of high scrap ratio, the total iron (T.Fe) content in slag during electric arc furnace smelting is relatively high, and the T.Fe content in slag is a key factor affecting the dephosphorization effect and the steel yield of electric arc furnaces (EAF). Currently, the primary method for controlling the T.Fe content in slag involves injecting carbon powder, optimizing carbon powder injection parameters is of great significance for improving EAF smelting quality. Taking the EAF smelting process with a 60% scrap steel ratio in a steel plant as the research object, focusing on the control effect of carbon powder injection flow rate on T.Fe in slag, the variation law of the T.Fe content in slag was systematically analyzed, and its influence mechanism on dephosphorization effect was explored.The research results show that after scrap melting, the T.Fe content in slag gradually increases with the progress of oxygen supply, and the mass fraction of T.Fe in the final slag can reach up to 35%. Carbon powder injection can effectively reduce the T.Fe content in slag and improve dephosphorization effect, but there is an optimal regulatory range for its flow rate. When the flow rate is lower than 60 kg/min, the T.Fe content in slag continues to rise in the middle and late stages of smelting,while exceeding 90 kg/min leads to carbon powder saturation and waste. Carbon powder injection enhances dephosphorization by reducing the proportion of FeO composite phase and increasing the proportion of phosphorus-rich 2CaO·SiO₂ phase in slag. The optimal effect is achieved when the flow rate is controlled at 55-70  kg/min. Compared with the working condition without carbon powder injection, the average T.Fe content in the final slag decreases from 29% to 20%, and the average dephosphorization rate increases from 60% to 80%.

Key words: EAF, slag, carbon injection, T.Fe content