Dephosphorization stability of hot metal by double slag operation in basic oxygen furnace
Wei Wu1,*,Shi-fan Dai1,Yue Liu2
1 Metallurgical Technology Research Department, Central Iron and Steel Research Institute, Beijing 100081, China 2 Hai Yi Tong Special Material Co., Ltd., Wuhan 430082, Hubei, China
Dephosphorization stability of hot metal by double slag operation in basic oxygen furnace
Wei Wu1,*,Shi-fan Dai1,Yue Liu2
1 Metallurgical Technology Research Department, Central Iron and Steel Research Institute, Beijing 100081, China 2 Hai Yi Tong Special Material Co., Ltd., Wuhan 430082, Hubei, China
ժҪ Double slag process was adopted to produce low-phosphorus steel from middle-phosphorus hot metal. To achieve a stable dephosphorization operation, conventional process was modified as follows: the blowing time was extended by approximately 1 min by reducing the oxygen supply flow rate; calcium ferrite pellets were added to adjust the slag composition and viscosity; the dumping temperature was lowered by 30-50��C by the addition of calcium ferrite pellets during the double slag process to prevent phosphorus in the slag from returning to the molten steel; and the bottom-blown gas flow was increased during the blowing process. For 40 heats of comparative experiments, the rate of dephosphorization reached 91% and ranged between 87% and 95%; the phosphorus, sulfur, manganese, and oxygen contents calculated according to the compositions of molten steel and slag as well as the temperature of molten steel at the end-point of the basic oxygen furnace process were similar to the equilibrium values for the reaction between the slag and the steel. Less free calcium oxide and metallic iron were present in the final slag, and the surface of the slag mineral phase was smooth, clear, and well developed, which showed that the slag exhibited better melting effects than that produced using the conventional slag process. A steady phosphorus capacity in the slag and stable dephosphorization effects were achieved.
Abstract��Double slag process was adopted to produce low-phosphorus steel from middle-phosphorus hot metal. To achieve a stable dephosphorization operation, conventional process was modified as follows: the blowing time was extended by approximately 1 min by reducing the oxygen supply flow rate; calcium ferrite pellets were added to adjust the slag composition and viscosity; the dumping temperature was lowered by 30-50��C by the addition of calcium ferrite pellets during the double slag process to prevent phosphorus in the slag from returning to the molten steel; and the bottom-blown gas flow was increased during the blowing process. For 40 heats of comparative experiments, the rate of dephosphorization reached 91% and ranged between 87% and 95%; the phosphorus, sulfur, manganese, and oxygen contents calculated according to the compositions of molten steel and slag as well as the temperature of molten steel at the end-point of the basic oxygen furnace process were similar to the equilibrium values for the reaction between the slag and the steel. Less free calcium oxide and metallic iron were present in the final slag, and the surface of the slag mineral phase was smooth, clear, and well developed, which showed that the slag exhibited better melting effects than that produced using the conventional slag process. A steady phosphorus capacity in the slag and stable dephosphorization effects were achieved.
��������:National Science and Technology Support Program for 12th Five Year Plan of China
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E-mail: wuweineu@163.com
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Wei Wu,*,Shi-fan Dai,Yue Liu. Dephosphorization stability of hot metal by double slag operation in basic oxygen furnace[J]. �й������ڿ���, 2017, 24(9): 908-915.
Wei Wu,*,Shi-fan Dai,Yue Liu. Dephosphorization stability of hot metal by double slag operation in basic oxygen furnace. Chinese Journal of Iron and Steel, 2017, 24(9): 908-915.
2017, Vol. 24 
