Effect of Thermal Charging of Iron Ore Pellets on the Reduction Rate and Compressive Strength in Gas-Based Reduction Process

Abstract:

Burden in gas-based direct reduction process is iron ore oxide pellet, which has experienced oxide roasting and cooling before reduction. However, it would be heated again in the reduction process. This may cause much energy waste and adverse effects on reduction process. In this paper, roasted pellets with and without cooling were charged for gas-based reduction respectively. The reduction rate and compressive strength during reduction were studied to reveal the effects of charging methods. Results showed that there is little difference on reduction rate between the two. However, the compressive strength of reduced pellets via thermal charging improves obviously. And nucleation and growth mechanisms of iron crystal grain in gas-based reduction were investigated by optical microscope (Leica DMRXP). The iron crystal nucleuses firstly form at the interface of grains and edge of wustite, and then gradually grow from surface layer to inner core as reduction proceeds. Thermal charging can promote the migration and accumulation of iron crystal grain effectively.

• Periodical: Advanced Materials Research (Volumes 532-533)
• Pages: 262-266
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.532-533.262
• Online since: June 2012
• Authors: Zhu Cheng Huang, Dao Guang Yang, Ling Yun Yi
• Keywords: Compressive Strength, Iron Ore Pellets, Reduction Rate, Thermal Charging

References

[1] Fan Xiaohui, Qiu Guanzhou, Jiang Tao. Present status and development prospect of iron ore direct reduction[J]. Ironmaking, Vol. 21(2002), No. 3: 53~56. In Chinese.

[2] Fang Jue. Process and Theory of Non-blast Furnace Ironmaking[M]. Beijing: Metallurgical Industry Press, 2002: 57~60. In Chinese.

[3] Huang Zhucheng. Cold-bonded pellet coal-based direct reduction technology and application[D]. Chang Sha: Central South University, school of minerals processing and bioengineering. In Chinese.

[4] Wang Youliu. Ferrous Metallurgy(Ironmaking)[M]. Beijing: Metallurgical Industry Press, 2005: 87~95. In Chinese.

[5] Krzysztof P, Kanchan M, Hana L. Effect of gas composition on the kinetics of iron oxide reduction in a hydrogen production process[J]. International Journal of Hydrogen Energy, 30 (2005): 1543~1554.

DOI: 10.1016/j.ijhydene.2004.10.013

[6] YI Ling-yun, HUANG Zhu-cheng, PENG Hu. The action rules of H2 and CO in gas-based direct reduction of iron ore pellets[J]. Journal of Central South University, In Press.

DOI: 10.1007/s11771-012-1274-0

[7] YI Ling-yun, HUANG Zhu-cheng, PENG Hu. Experimental research on the novel process of iron ore direct reduction by coal gas[J]. Advanced Materials Research, Vols. 311-313 (2011): 891~897.

DOI: 10.4028/www.scientific.net/amr.311-313.891

[8] Zhucheng Huang, Lingyun Yi, Tao Jiang. Mechanisms of strength decrease in the initial reduction of iron ore oxide pellets [J]. Powder Technology, (2012), doi: 10. 1016/j. powtec. 2012. 01. 013.

DOI: 10.1016/j.powtec.2012.01.013

[9] R.D. Liu. The basis of metallurgical thermal furnace[M]. Metallurgical Industry Press, Beijing, 1980: 226~227. In Chinese.

[10] G. H. Gage, D.R. Boilier. The heat and mass transfer phenomena in metallurgy[M]. Metallurgical Industry Press, Beijing, 1981: 209~219. In Chinese.