The 12 t medium-frequency furnace of ABP Company is used to smelt molten iron, and the charge ratio is 20%~30% of the return charge+70%~80% of the packed scrap. The packaging scrap uses FAW body scrap, with stable chemical composition, good consistency, low sulfur content, and a packaging size of 300 mm × 300 mm × 390 mm, using high-temperature graphitized low sulfur carburetor, its main components are w (C) ≥ 98%, w (S) ≤ 0.03%, w (N) ≤ 0.03%, with high absorption rate and good carburetion effect. Silicon carbide is used for pretreatment to increase the nucleation ability of molten iron.
After the molten iron in the medium frequency furnace is melted, the temperature is raised to 1 540~1 550 ℃, and the temperature is kept for 20 minutes. The purity of the molten iron is improved after the high temperature overheating, which can better conduct the vermicular treatment and obtain good metallographic structure.
The amount of molten iron in each ladle is (1800 ± 10) kg. The molten iron ladle is transported to the pouring line by monorail car. After slagging, it is poured into the peristaltic treatment bag. After temperature measurement, the peristaltic pretreatment is carried out. The treatment temperature is 1 480~1 490 ℃. The magnesium wire and inoculation line are automatically added according to the equipment prompt. After pre-treatment, SinterCast sampling analysis will be carried out, and post-treatment will be carried out according to the analysis results. The equipment will automatically add magnesium line and inoculation line. After treatment, temperature measurement and pouring shall be carried out. The pouring temperature shall be 1 420~1 440 ℃. Four boxes of molten iron shall be poured in each package. The weight of molten iron in each box is about 450 kg. The pouring shall be completed within 8 minutes, and the remaining molten iron in each package shall be poured out.