COURSE50 (CO2 ultimate reduction in steelmaking process by innovative technology for Cool Earth 50) carried out COG and reformed COG (RCOG) injection operation trials at LKAB's experimental blast furnace in Luleå in cooperation with LKAB and Swerea MEFOS. Operation trials were successfully carried out. Input of C in both COG and RCOG injection periods decreased comparing the base period, because of increase in H2 reduction instead of C direct reduction that is a huge endothermic reaction. However poor penetration depth of injected gas from shaft tuyere made furnace efficiency worse. Hot top gas injection increased temperature of top gas and upper part of the furnace. Efficiency of hot top gas injection was not clear as sinter degradation did not occur in the base period.KEY WORDS: COURSE50; experimental blast furnace; blast furnace; CO2 emission; H2; COG; reformed COG; injection; hot top gas; sinter degradation. PrefaceCOURSE50 (CO2 ultimate reduction in steelmaking process by innovative technology for Cool Earth 50) is a national project for development of technologies for environmentally harmonized steelmaking process to achieve drastic CO2 emissions reduction in steel industry. Main targets of COURSE50 project are development of technologies to reduce CO2 emissions from blast furnace and development of technologies to capture, separate and recover CO2 from blast furnace gas. CO2 reduction technology from blast furnace consists of research of control reactions for reducing iron ore with hydrogenous reducing agents such as coke oven gas (COG) or reformed COG (RCOG). RCOG is amplified its hydrogen content in COG by utilizing newly developed catalyst and unused waste heat. Also a technology to produce high strength and high reactivity coke for reduction with hydrogen is under development.RCOG will be injected to the blast furnace through tuyeres located at lower part of the shaft of blast furnace, and COG will be injected through blast tuyeres to utilize CH4 combustion.Amount of O2 enrichment to the hot blast air has to be increased when COG is injected to the blast tuyere to maintain the flame temperature constant to compensate for heat of decomposition of hydrocarbon. It results in decrease in upper part temperature and decreased upper part temperature prolongs the residence time for sinter where disintegration is promoted. In addition, H2 may promote sinter deterioration. To prohibit prolonged residence time for sinter at low temperature range, top gas is partly combusted is injected in the upper shaft for temperature control. We call it hot top gas injection in this article.Basic and remarkable results are conducted through various laboratory tests and mathematical model calculation in COURSE50 project.3,4) H2 in COG or RCOG is expected to react with ferrous material very fast and to replace C as reducing agent of blast furnace.However, reaction in the blast furnace is much complicated because it is dominated by burden and gas distribution

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A controlling method of the radial mixed coke ratio distribution under high coke mixed charging, which is called FCG (Flow Control Gate) dynamic control method was studied with the aim of stable operation with high productivity and low RAR at Chiba No. 6 blast furnace. For this purpose, scale model experiments and mathematical burden distribution model calculations were performed. The effects of FCG dynamic control with ore and coke simultaneous discharging from the respective top bunkers on the mixed coke ratio distribution were examined and applied to Chiba No. 6 blast furnace. After application of FCG dynamic control, improvements of gas utilization efficiency: +0.2%, gas permeability at cohesive zone (the part of lower shaft): -14.7% and coke ratio: -4.2 kg/t (with constant RAR) were confirmed. Since June 2007, high productivity operation with low RAR has been conducted at Chiba No. 6 blast furnace.