Isothermal kinetics of the first stage reduction of magnetite cold bond pellets with carbon monoxide

Abstract

The reduction of Fe₃O₄ to Fe is accomplished in two stages. In order to understand the reduction mechanism of magnetite cold bond pellets during the first period of heating-up process, it is necessary to study the kinetics of the reaction. In this work, the first stage of reduction of magnetite cold bond pellets, that is the reduction from Fe₃O₄ to FeO, has been investigated using an isothermal thermogravimetric method. Isothermal experiments were carried out at 750°C, 800°C, 850°C and 900°C, respectively. The results showed that the reaction was controlled by chemical reaction below 800°C, whereas, at higher temperature, it was controlled by a mixed controlled mechanism of chemical reaction and Ginstling-Brounshtein diffusion as well.

Keywords

kinetics / thermogravimetry / reduction / cold bond pellet

References

[1] MurayamaT, OnoY, KawaiY. Step-wise reduction of bematite pellets with CO-CO₂ gas mixtures. J Iron Steel Inst Jpn, 1977, 63(7): 1099-1107

[2] RayH S, KunduN. Thermal analysis studies on the initial stages of iron oxide reduction. Thermochim Acta, 1986, 101: 107-118

[3] PaulS, MukherjeeS. Non-isothermal and isothermal reduction kinetics of iron ore agglomerates. Ironmaking and Steelmaking, 1992, 19(3): 190-193

[4] RayA K, PrasadK K, SenP K. Kinetics of reduction of iron ore with carbon monoxide. Trans India Inst Met, 1994, 47(4): 215-219

[5] Trujic V, Markotic A. Thermogravimetric and laboratory investigations of magnetite concentrate reduction by solid reducers. Transactions of the ISS, 1991(1): 51–57

[6] Kiselve V A, Permyakova L I, Leontev L I, et al. The reduction kinetics of ore-carbon pellets prepared from lisakovsk roasted magnetic concentrate. Izv Akad Nauk SSSR Met (in Russian), 1982(6): 33–36

[7] SeatonC E, FosterJ S, VelascoJ. Reduction kinetics of hematite and magnetite pellets containing coal char. Trans Iron Steel Inst Jpn, 1983, 23(6): 490-496

[8] GaoX, DollimoreD. The thermal decomposition of oxalates. Part 26: A kinetic study of the thermal decomposition of manganese (II) Oxalate dihydrate. Thermochim Acta, 1993, 215: 47-63

[9] MoDingchengMetallurgical kinetics, 1987, Changsha, Central South University of Technology Press: 193-204(in Chinese)