The Direct Reduction of Iron Ore with Hydrogen

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.

Hydrogen‐Based Direct Reduction of Iron Oxides Pellets Modeling

“…[17] The hydrogen-based process is characterized by a complex chemomechanical interplay of the different mechanisms involved, specifically the underlying reactions, mass transport, and volume changes. [18] Among the reaction steps, wüstite reduction to iron is the slowest one by nearly an order of magnitude lower reaction kinetics compared with the other two steps; therefore, it plays an important role in determining the overall rate of the reactions. [19] Now, many analytical models can be found in the literature in order to predict the kinetics behavior of direct reduction as a function of the many factors influencing the overall process.…”

Water Splitting by MnOx/Na2CO3 Reversible Redox Reactions

“…A 0.05 m internal vibrated fluidized bed reactor was used. The advantages of using solar concentrated as a heat source were recently highlighted in number of publications with respect of solar-topower uses [23][24][25], solar-driven thermo-chemical reactions [4,25] and solar-driven physical applications [26][27][28]. Water/steam and N2 carrier gas were preheated in a coil heat exchanger within the cavity as illustrated at the right of the reactor in Figure 4.…”

“…These COPs proclaimed the leading role of renewable energy in solving climate problems. The wider use of hydrogen was advocated [1,2] through, e.g., hydrogen-enriched natural gas [3], the direct reduction of iron ore [4], the use of hydrogen in the minerals' processing [5], and the production of CO 2 -based synthetic natural gas [6], among others. It is important to assess the ways that hydrogen production can help to meet the renewable energy goals.…”

Water splitting by MnFe2O4/Na2CO3 reversible redox reactions

“…According to Chen et al, 43 the oxygen release (step 2 of the reaction cycle) between layered Na(Mn 1/3 Fe 2/3 )O 2 and CO 2 is fairly slow and requires >3 h to be completed. 44,45 This was further investigated by TGA, where it was demonstrated that the reduction step preferably requires 4.5 to 6 h. Stoichiometrically, the yield should be 0.5 mol H 2 per mol MnFe 2 O 4 , which is only closely achieved for the coprecipitated reactant. Regrinding of the reactants between the cycles slightly increased the H 2 yield.…”