To discuss sinter condition for lowering dripping temperature of molten iron and enhancing reducibility, reduction behavior of sinter samples with extensive range of chemical composition was measured with reduction test under load. Basicity was found to have dominant influence on dripping temperature and should be in the range between 1.0 and 1.5. A further decrease in dripping temperature was achieved by decreasing Al 2 O 3 content and increasing MgO content in sinter, which was related with low liquidus temperature, low viscosity and fast smelting-reduction of slag containing low FeO content. In contrast, reducibility and mineralogy of sinter influenced softening-melting behavior as well. Increasing fine pores could improve softening-melting behavior as a result of enhancing reducibility. Finally optimized sinter, containing 1.0-1.5 basicity, low Al 2 O 3 and high MgO content was proposed. This chemical composition of sinter could lower dripping temperature by 80°C with fairly high permeability of sinter layer compared to conventional sinter. Possibility of the further improvement of softening-melting behavior at a constant chemical composition with controlling sinter mineralogy was discussed.KEY WORDS: agglomeration; iron ore sinter; reduction; dripping; softening-melting; porosity; microstructure.* Notification: As the word expressing the same phenomenon is different among past papers, authors defined the temperature at which the first drip takes place as dripping temperature and the temperature at which pressure drop starts to increase as softening-melting temperature in the present study.teristics such as grain size of hematite and distribution of gangue minerals seems to have the influence on reduction behavior via forming microstructure and pore structure during reduction even at a constant chemical composition of sinter. However the information on sinter mineralogy on high-temperature reduction is still limited. 17) In the present paper, reduction tests under load of sinter with extensive range of chemical composition have been performed and optimization of chemical composition, pore structure and microstructure was discussed to attain suitable properties of sinter for the innovative blast furnace. In particular, conditions for low-temperature drip of molten iron has been focused. Experimental Methods Sinter and PelletsSinter samples with different chemical compositions (basicityϭ1.2-2.6, SiO 2 ϭ3.0-6.8 mass%, Al 2 O 3 ϭ1.1-3.2 mass%, MgOϭ0.2-2.5 mass%) were produced by using a pot simulator whose diameter was 30 cm and 60 cm in bed height. Blending conditions of iron ores and fluxes were changes to attain desired chemical compositions. Table 1 shows chemical compositions of iron ores and fluxes used in the present study. Ore A is Brazilian soft hematite ore and Ore B is Brazilian hard hematite ore. Ore C is Australian soft hematite ore. Ore D is Indian soft hematite ore. Ore E and Ore F are Australian Pisolitic limonite ores. Coke content in a raw mixture was adjusted to maintain sufficient value of si...

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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