Reduction of CO2 Emissions by Use of Pre-reduced Iron Ore as Sinter Raw Material

Abstract

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.

Effects of Adding Iron Ores-based Calcium Ferrites to the Sinter Mix on Sinter Quality and Reduction of CO₂, NO and SO₂

“…Therefore, the primary attempt to decrease the CO 2 emission from the sinter plant is to reduce the ratio of fuel present in the sinter mix. 5,18) However, the aforementioned reduction in the amount of fuel will decrease the energy supplied to the sinter bed, and then affect the sintering temperature profile, which will lead to a decrease in the amount of melt. This melt phase is highly required for bonding of the particles present in the sinter mix, which is directly related to the sinter strength.…”

“…3,4) In the steelworks, carbon is mainly consumed in the operation of the blast furnaces and sinter plants. 5) Furthermore, the decrease in the amount of carbon used in those areas would end up with a reduction in the emission of not only CO 2 but also other harmful gases such as nitrogen oxide (NO) and sulfur dioxide (SO 2 ). 6,7) Iron ore sintering is an agglomeration process of a mixture of ore fines mainly consisting of iron ores, fluxes and fuel, which produces sinters with suitable chemical and physical properties for the operation of the blast furnace.…”

Iron Ore Agglomeration Technologies

“…JFE Steel Corporation developed a hydrogen-based gas fuel injection technology, reducing CO 2 emissions by 60,000 tons/year [50]. Yabe and Takamoto proposed a process that used pre-reduced iron ore as sinter raw material (produced by reducing the iron ore to the degree of wüstite with blast furnace gas [51]). Coke breeze consumption is reduced (40,000 tons/year less of coke breeze in integrated plant of 4 Mt/year hot metal production) and 50,000-12,000 tons CO 2 /year less by using 10% pre-reduced iron ore.…”

Reduction Mechanism of Fe_xO — Graphite Composite under Elevating Temperature

“…Some recycling materials, e.g., mill scale contains wüstite, and further wüstite containing materials will be obtained by prereduction of iron ores utilizing, e.g., certain gas having low reducing ability like blast furnace gas. 7) Wüstite has wide range solid solution of iron and oxygen, described as Fe x O. Reduction within the Fe x O region should be also considered.…”