Numerical Investigation into Gas-Particle Inter-Phase Combustion and Reduction in the Flash Ironmaking Process

Abstract

Despite the dominance of the blast furnace ironmaking process, more attention is being paid to the new technologies with lower energy consumption and carbon dioxide emissions. A novel flash ironmaking technology using pulverized coals and iron concentrates as raw materials, which is different from flash ironmaking with the reductive gas as the reducing agent, is studied. In order to obtain the flow patterns, temperature, and gas composition distribution, as well as particle trajectories in the reaction shaft of the flash ironmaking furnace, the Euler–Lagrangian model with a custom user defined function (UDF) code is used to simulate the processes of the fluid flow, heat and mass transfer, and chemical reactions, including the combustion reaction of pulverized coals and reduction reaction of iron concentrates. The results indicate that the flow patterns, temperature, and gas composition distributions present symmetrical distribution characteristics. The central oxygen expands rapidly after entering the reaction shaft and its distribution is approximately bell-shaped. The temperature distribution in the reaction shaft is wing-shaped. The maximum temperature, 2615 K, is reached at 5 m below the roof of the reaction shaft. The O2 is quickly consumed after entering the reaction shaft. At 6 m below the roof of the reaction shaft, the oxygen concentration becomes almost zero, with the CO concentration reaching the highest. The Fe2O3 and FeO in the iron concentrates are mostly reduced to Fe at 9 m below the roof of the reaction shaft, and more than 95 wt% iron particles could be obtained within 1.2–7.7 s.

A Kinetic Study on the Reduction of Single Magnetite Particle with Melting Products at High Temperature Based on Visual and Surface Analytical Techniques

“…However, at high temperature, the other two steps from Fe 3 O 4 to FeO and FeO to Fe were found to take place in parallel [9]. At high temperature, during the flash ironmaking process, it was found that Fe 2 O 3 and FeO in the iron concentrates were mostly reduced to Fe within 1.2-7.7 s, occupying 95 wt.% of total iron particles [7]. In addition, it was found that the topochemical process from Fe 2 O 3 to FeO was initially reaction-controlled [15,16].…”

“…To solve these issues, alternative and innovative ironmaking technologies have been developed, such as COREX, Midrex, FINEX, HIsarna, and flash ironmaking [4,5]. Among these, the novel flash ironmaking technology, which was conceived by Sohn et al from the University of Utah, has received much attention in recent years [6][7][8]. This technology can omit the complicated procedures, remove the energy consumption of the coking and sintering processes, and improve energy efficiency.…”

Numerical Analysis of Flash Ironmaking Process in a Newly Proposed Counter-Current Downer

“…Simultaneous gasification and reduction were expected to be realized in the pilot-scale furnace. 8,9 The researchers have already customized various high-temperature gas-particle reactors, divided into gas conveyed systems and coupling reactors. The former was used for laboratory-scale research with ready-made reductive gas, while the latter was close to a bench-scale practice using methanol combustion/coal gasification to generate the qualified reductive gas and necessary heat.…”