Abstract:
The dephosphorization potential of converter slag is huge. After gasification dephosphorization in the slag splashing protection stage,it can be used for the next furnace to achieve low-temperature dephosphorization of molten steel,which can not only avoid the enrichment of P elements,but also ensure efficient and convenient utilization of the slag. The test research of converter slag gasification dephosphorization cycle steelmaking were carried out in Tangshan Iron and Steel,Chenggang and Shougang Jingtang. Industrial trials were conducted on single slag,semi steel,and duplex converter processes. The results show that the highest gasification dephosphorization rate of the end point slag of the single slag smelting converter at Tangshan Iron and Steel Group Co.,Ltd. is about 40.37%,followed by the semi steel smelting converter at Chengde Iron and Steel Group Co.,Ltd.,which is 35.07%,and the lowest gasification dephosphorization rate of the slag of the Jingtang dephosphorization furnace at Shougang Iron and Steel Group Co.,Ltd. is 29.26%. The reaction temperature has the greatest impact on the gasification dephosphorization rate,and the slag mass transfer rate often limits the gasification dephosphorization effect.The gasification dephosphorization slag cycle steelmaking furnace runs efficiently and stably,and the P mass percent in the end point molten steel is relatively stable,with an average of 0.024%,0.026%,and 0.028%,which meet the end point composition requirements of smelting steel types. Compared with conventional smelting furnaces,the consumption of lime and iron and steel materials per ton of steel in the test furnaces has been reduced in different proportions,The average consumption of lime per ton of steel in Tangshan Iron and Steel Co.,Ltd.,Chenggang Iron and Steel Co.,Ltd.,and Shougang Jingtang Iron and Steel Co.,Ltd. test furnaces decreased by 4.54 kg,4.31 kg,and 1.21 kg,respectively,and the average consumption of iron and steel materials per ton of steel decreased by 4.43 kg,3.24 kg,and 2.15 kg,which can produce economic benefits and energy saving and emission reduction effects. By comparing and analyzing the phase of final converter slag and gasification dephosphorization slag after reaction,it can be seen that P
2O
5 in the slag is gasified and reduced to P
2 gas under high temperature conditions,a part of P
2 reacts with Fe elemental substance to form Fe
xP phase,and the other part of P
2 is removed from the slag in the form of gas.