- Title
- Interaction of ferrous burden materials in the cohesive zone of the ironmaking blast furnace under hydrogen operation
- Creator
- Barrett, Nathan Thomas
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2024
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- In this study, enrichment of the ironmaking blast furnace with hydrogen was investigated and the changes to mixed burden interaction mechanisms under hydrogen operation was studied in detail. Numerical studies determined that at most, 19.5 kg-H2/t-HM could be injected into the modelled blast furnace, replacing 34 kg-PCI/t-HM and reducing equivalent CO2 emissions by 8 – 14% (dependant on in-furnace behaviour of hydrogen). From this injection of hydrogen, the bosh gas hydrogen concentration increased from 6 vol% to 20 vol%, and the hydrogenous fraction of the reducing gas increased from 0.15 to 0.37. The hydrogen in the furnace gas primarily replaced nitrogen. Laboratory softening and melting experiments were conducted with 15% hydrogen added to the inlet gas (replacing nitrogen). Lump, sinter and mixed burdens comprised of 20% lump and 80% sinter were compared under standard test conditions and simplified hydrogen conditions. It was demonstrated that with the addition of hydrogen, lump ore performance improved markedly, with the maximum pressure drop and S value decreasing significantly. Conversely, sinter demonstrated a significant increase in maximum pressure drop and S value. Mixed burdens demonstrated that an interaction between the burdens still occurred with the addition of hydrogen. Inclusion of hydrogen was demonstrated to promote carbon deposition (<700 °C) and gasification (>700 °C). Through development and application of novel techniques, mechanisms of burden interaction were studied in detail under both traditional and hydrogen enriched blast furnace conditions. For lump particles with low metallisation (as were present under traditional conditions), the interaction with sinter was initiated by low temperature fayalitic liquids from the lump. The interaction with sinter acted to suppress these liquids through stabilisation of phases such as merwinite, melilite, olivine and anorthite (depending on local availability of MgO). For lump particles with high metallisation, where Al2O3 and MgO were locally present, little liquid was formed in either burden at 1300 °C. In the absence of Al2O3 and MgO the interaction was initiated by liquid formation in sinter. In this case the interaction with lump acted to suppress liquid formation through stabilisation of larnite, rankinite and wollastonite phases. Addition of hydrogen resulted in more highly metallised lump particles (higher degree of reduction), altering the dominant interaction mechanisms of mixed burdens. The addition of hydrogen was demonstrated to promote gas carburisation in sinter burden, resulting in a lowering of the first dripping temperature and contributing to the observed softening and melting performance. The same carburisation was not observed for lump ore, which maintained a highly metallic solid structure up to at least 1450 °C. The findings of this thesis contribute a fundamental understanding of real interaction conditions at the interface of dissimilar burdens, both under traditional and hydrogen enriched operation. These findings are expected to aid in burden design for future operations.
- Subject
- blast furnace; ironmaking; metallurgy; slag; hydrogen; interaction
- Identifier
- http://hdl.handle.net/1959.13/1510765
- Identifier
- uon:56450
- Rights
- Copyright 2024 Nathan Thomas Barrett
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 77 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 399 KB | Adobe Acrobat PDF | View Details Download |