Thermal Decomposition Behaviour of Fine Iron Ore Particles

Abstract

In the smelting cyclone of HIsarna process, both thermal decomposition and gaseous reduction of iron ore contribute to the expected pre-reduction degree about 20%. However, the fine ore reduction and melting process in the smelting cyclone is extremely fast and it is very difficult to differentiate between the thermal decomposition and gaseous reduction. This study focused on the thermal decomposition mechanism of the fine iron ore under different conditions. Firstly, the theoretical evaluation has been conducted based on the thermodynamics, and then the laboratory investigation was conducted in three stages with three reactors: the TGA-DSC, the electrically heated horizontal tube furnace and the High-temperature Drop Tube Furnace (HDTF). According to the experimental results of the first two stages and the theoretical evaluation, it was found that the temperature of intensive thermal decomposition of Fe2O3 in the inert gas environment is in the range of 1 473-1 573 K, while the thermal decomposition of Fe3O4 could be sped up when the temperature is above 1 773 K in the inert gas. Temperature plays an important role in the thermal decomposition degree and reaction rate. Finally, it was found that the thermal decomposition of the individual iron ore particles took place very rapidly in the HDTF and no significant influence of the particle size and residence time (t ≤ 2 020 ms) on the equivalent reduction degree could be observed, when the particle diameter was smaller than 250 μm in the CO2 gas.

Reduction Kinetics of Fine Hematite Ore Particles with a High Temperature Drop Tube Furnace

“…According to the previous study, 12,13) the thermal decomposition of fine hematite ore took place in the first 210 ms in the inert gas and no further thermal decomposition reaction could be detected after 210 ms. In the reducing gas, the thermal decomposition and reduction of hematite ore took place simultaneously in the first 210 ms and only reduction took place after 210 ms.…”

“…............... (13) In order to give more evidence for the reaction mechanism of gas-solid reduction, E a was also calculated by the Friedman's method that belongs to model-free method. 18,29) This method is a differential method as shown in Eq.…”

Abundance and Emission Flux of the Anthropogenic Iron Oxide Aerosols From the East Asian Continental Outflow

“…Comparison between experimental and theoretical results for the color ratio suggests that FeO x particles in a laser beam become spherical iron droplets through melting and thermal decomposition. A more detailed discussion can be found in Figure S1 (Huffman & Stapp, ; Johnson & Christy, ; Qu et al, ).…”

Influence of CGD structure on burden descending behavior in COREX shaft furnace

“…With the increasing of environment pressure and the scarcity of high quality coking-coal resource, a series of alternative ironmaking processes have been developed rapidly in recent decades, such as COREX, Midrex, HYL, Finex, etc. [1][2][3][4]. In these processes, COREX, a smelting reduction process designed by Siemens VAI, has been industrialized successively in South Africa, Korea, India and China [5][6][7].…”