1990 Volume 30 Issue 5 Pages 362-371
For the simultaneous control of Si and S contents in pig iron, a simultaneous injection of pulverized coal and flux (dolomite in this research) into blast furnace tuyeres was proposed. Fundamental researches were performed on slag formation property, SiO gas generation reaction and transport properties of pulverized coal-dolomite mixture to investigate merits and presumed problems of simultaneous injection of pulverized coal and dolomite. The significant improvement of slag formation property and the suppression of SiO gas generation reaction were confirmed. Pressure drops in both horizontal and vertical transport pipelines were experimentally evaluated. Distribution characteristics to tuyeres and abrasion of transport pipeline of pulverized coal and dolomite mixture were found to be no problem for commercial application. Based on the fundamental researches, a commercial test operation with simultaneous injection of pulverized coal of 20 kg/THM and dolomite of up to 15 kg/THM were performed at Kokura No. 2 blast furnace, Sumitomo Metal Industries, Ltd., for 2 weeks. Si and S contents in pig iron were decreased through dolomite injection of 15 kg/THM by 0.06 and 0.005%, respectively. The increase of corrected coke rate of 6.2 kg/THM was obtained by dolomite injection of 15 kg/THM. No harmful change of inner furnace state was observed and the stable furnace operation can be expected with simultaneous injection of pulverized coal and dolomite.
