Abstract
The steel industry represents about 7% of the world’s anthropogenic CO2 emissions due to the high use of fossil fuels. The CO2-lean direct reduction of iron ore with hydrogen is considered to offer a high potential to reduce CO2 emissions, and this direct reduction of Fe2O3 powder is investigated in this research. The H2 reduction reaction kinetics and fluidization characteristics of fine and cohesive Fe2O3 particles were examined in a vibrated fluidized bed reactor. A smooth bubbling fluidization was achieved. An increase in external force due to vibration slightly increased the pressure drop. The minimum fluidization velocity was nearly independent of the operating temperature. The yield of the direct H2-driven reduction was examined and found to exceed 90%, with a maximum of 98% under the vibration of ~47 Hz with an amplitude of 0.6 mm, and operating temperatures close to 500 °C. Towards the future of direct steel ore reduction, cheap and “green” hydrogen sources need to be developed. H2 can be formed through various techniques with the catalytic decomposition of NH3 (and CH4), methanol and ethanol offering an important potential towards production cost, yield and environmental CO2 emission reductions.
Highlights
The successive processes of sinter belt, blast furnace and converter operate at extremely high temperatures, being energy-intensive and producing significant amounts of CO2
Analyzed a new route for making steel from iron ore based on the use of H2, with a 90% reduction in CO2 emissions compared to those of the blast-furnace route
To increase the fluidity of the fine of the fine particles, fluidization must be performed with the help of an external force particles, fluidization must be performed with the help of an external force to decrease the to decrease the interparticle Van der Waals force
Summary
Most steel mills are currently using the blast furnace principle, fuelled by mostly coal, coke and coke oven gas. The successive processes of sinter belt, blast furnace and converter operate at extremely high temperatures, being energy-intensive and producing significant amounts of CO2. The steel industry represents about 7% of the world’s anthropogenic CO2 emissions. Within the objectives of COP21 (Paris, 2015), the target of steel mills is to reduce the CO2 emissions from the current (nearly) 3000 Mton/year to below 500 Mton/year. The use of renewable energy sources is, a topic of major development, and the CO2 -lean direct reduction of iron ore with hydrogen is considered to offer high potential. Two alternative direct H2 ore reductions (Figure 1, right-side) and the traditional fossil-fuel blast furnace operation (Figure 1, left-side) are illustrated in Figure 1 below
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