In order to reduce CO2 emissions at an ironmaking process, it is an effective measure to decrease a bonding agent rate at an iron ore sinter plant. In this study, effect of using a pre-reduced iron ore as a part of a sinter raw material on a sintering process was investigated mainly from a viewpoint of decreasing a bonding agent rate.Two brands of pisolitic iron ores were reduced up to wustite at 1 173 K with reducing gas of which an oxidation degree was 55%. The pre-reduced iron ore was stable against reoxidation in the atmosphere and through a cyclic wet and dry treatment.Two brands of pisolitic iron ores and a Marra Mamba iron ore were pre-reduced and then used in a sinter pot test. A use of the pre-reduced iron ore was effective in decreasing a bonding agent rate at a given productivity. The reoxidation heat of the pre-reduced iron ore was estimated to be less than the combustion heat of the bonding agent being saved by use of the pre-reduced iron ore. The reoxidation heat is more effective in the sintering process than the combustion heat. The decrease of the bonding agent resulted in reduction of NOx emissions.A mass and heat balance shows that a use of a pre-reduced iron ore as a sinter raw material enables reduction of CO2 emissions not only at an ironmaking process but also at a whole integrated steel works.KEY WORDS: sinter plant; blast furnace gas; pre-reduced iron ore; coke breeze saving.

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Synopsis :In order to reduce CO 2 emissions at an ironmaking process, it is an effective measure to decrease a bonding agent rate at an iron ore sinter plant. In this study, effect of using a pre-reduced iron ore as a part of a sinter raw material on a sintering process was investigated mainly from a viewpoint of decreasing a bonding agent rate. Two brands of pisolitic iron ores were reduced up to wustite at 1173 K with reducing gas of which an oxidation degree was 55%. The prereduced iron ore was stable against reoxidation in the atmosphere and through a cyclic wet and dry treatment. Two brands of pisolitic iron ores and a Marra Mamba iron ore were pre-reduced and then used in a sinter pot test. A use of the pre-reduced iron ore was effective in decreasing a bonding agent rate at a given productivity. The reoxidation heat of the pre-reduced iron ore was estimated to be less than the combustion heat of the bonding agent being saved by use of the pre-reduced iron ore. The reoxidation heat is more effective in the sintering process than the combustion heat. The decrease of the bonding agent resulted in reduction of NOx emissions.A mass and heat balance shows that a use of a pre-reduced iron ore as a sinter raw material enables reduction of CO 2 emissions not only at an ironmaking process but also at a whole integrated steel works.