Development of Gas Fuel Injection Technology in Iron Ore Sintering Process

JFE Steel Corporation developed a technology for injection of hydrogen-based gas fuel in sintering machines, Super-SINTER (Secondary-fuel Injection Technology for Energy Reduction). The technology makes it possible to greatly reduce CO2 emissions in the sintering process, and was successfully applied to a commercial sinter plant for the first time in the world. In ordinary sintering process, after coke breeze is mixed with iron ore and limestone, raw materials are charged and sintered in sintering machine. In order to produce high strength and high reducibility sintered ore, it is necessary to keep the sintering temperature between 1,200 degrees and 1,400 degrees during sintering. In the temperature below 1,200 degrees, the strength of sintered ore decreases because raw materials do not melt enough. In the temperature over 1,400 degrees, the strength and reducibility decrease by increasing glassy silicate. With Super-SINTER technology, it is possible to extend the optimum temperature zone by injecting a hydrogen-based gas fuel from the upper side of the charged raw materials as a partial substitute for coke breeze. As a result, the energy efficiency of the sintering process was greatly improved, and it has been achieved to reduce CO2 emissions by a maximum of approximately 60,000 tons/year. Moreover, the new technology of hydrogen-based gas fuel injection with oxygen enrichment has been developed to furthermore improve Super-SINTER technology. This technology can extend the optimum temperature zone wider than ordinary Super-SINTER by increase of combustion rate of fuels with oxygen enrichment. As a result, sinter productivity with high quality was improved greatly.