Thermal Properties of Carbon-Containing Iron Ore Composite Prepared by Vapor Deposition of Tar for Limonite
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UCTION
THE iron and steel industry is encountering numerous challenges on a global scale including appreciation/ depletion of ironmaking resources, excessive energy consumption, and significant CO2 emission. It is important that solutions are found for these three major problems related to resources, energy, and environment for the continued development of this industry. Recently, lowering of the thermal-reserve zone in blast furnaces has been considered as an effective strategy for reducing the consumption of energy and the reduction of CO2 emissions during the ironmaking process.[1] In addition, it is also important to develop new technologies for the raw materials used in ironmaking that can utilize low-grade iron ore (limonite) that contains a large amount of a-FeOOH and gangue for blast furnaces and sintering machines. This could effectively address the YUUKI MOCHIZUKI and NAOTO TSUBOUCHI are with the Center for Advanced Research of Energy and Materials, Hokkaido University, Sapporo 060-8628, Japan. Contact e-mail: [email protected] Manuscript submitted June 2, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS B
aforementioned resource problem. Therefore, it is necessary to develop methods to produce ironmaking raw materials with high-reduction reactivity. These materials should also be strong to ensure permeability in blast furnaces. It is well known that the reduction disintegration phenomenon caused by volume expansion during reduction from Fe2O3 to Fe3O4 in iron materials reduces permeability in the blast furnace.[2,3] Therefore, it is also important to develop low-reduction disintegration (RDI) ironmaking raw materials for use in blast furnaces. As such, the development of ironmaking raw materials with low RDI and high-reduction reactivity is necessary. In recent years, the utilization of carbon-containing iron ores (composites) with rapid reduction ability for use in blast furnaces has been considered promising for lowering of the thermal-reserve zone in blast furnaces because the carbonaceous materials and iron oxide in the composite are in a close contact. This has been addressed in several works.[4–10] The production of composites using chemical vapor infiltration (CVI) has been investigated as a possible production method.[9–13] In this approach, gaseous-tar derived from the pyrolysis of carbon resources is infiltrated and the carbonaceous materials derived from tar is deposited into pores in dehydrated-limonite, resulting in close contact between
Table I.
Analyses of Samples Used in This Study Elemental Analysis Wt pct-dry
Sample Limonite Cold-Bonded Pellet COG Tar Low-Strength Coke High-Strength Coke
Code
Fe
Si
Al
Ni
Mg
Ca
C
H
N
S
IL DP — LC HC
43 34 — — —
3.2 2.4 — — —
1.8 1.0 — — —
1.1 — — — —
0.6 — — — —
— 9.3 — — —
— 19 91 91 86
— — 5.3 0.2 0.2
— — 1.10 0.08 0.14
— — 0.5 0.3 0.4
carbonaceous materials and iron oxide. (In this report, carbon-species derived from tar are defined as carbonaceous materials, which are hydrocarbon species including C, H, N, S, and O). Theref
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