E-Thesis 313 views
Investigating the suitability of Subcoal® as an alternative blast furnace reductant. / FAWAZ OJOBOWALE
Swansea University Author: FAWAZ OJOBOWALE
DOI (Published version): 10.23889/SUThesis.66937
Abstract
The blast furnace is the most widely used means to producing pig iron for steel production. In the blast furnace, iron oxide is reduced to metallic iron using carbonaceous materials usually from fossil sources. The steel industry aims to reduce coke consumption and minimise CO2 emissions by improvin...
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Swansea, Wales, UK
2024
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Holliman, P. and Greenslade, M. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa66937 |
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| Abstract: |
The blast furnace is the most widely used means to producing pig iron for steel production. In the blast furnace, iron oxide is reduced to metallic iron using carbonaceous materials usually from fossil sources. The steel industry aims to reduce coke consumption and minimise CO2 emissions by improving the energy efficiency of the process and by investigating the use of carbon-neutral materials. Climate change is being driven by increases in greenhouse gases which absorb heat radiation in the atmosphere which is changing global temperatures and weather patterns. The most abundant greenhouse gas is carbon dioxide which is produced by combustion of fossil fuels such as coal, oil and natural gas. Fossil fuels are widely used in energy intensive industries such as the steel industry. This thesis, which is co-sponsored by the EPSRC and Tata Steel – Port Talbot, reports studies of alternatives to fossil fuels which have the potential to replace them particularly in blast furnace ironmaking. The alternative carbon source studied has been Subcoal® which is a refuse-derived fuel (RDF) produced by N&P Ltd. Subcoal® consists of non-recyclable carbon-based waste (mainly paper and plastic) which would otherwise be landfilled. Instead, this material is processed by sorting and heating before being extruded into pellets which was the main material supplied for this thesis work. The thesis describes an initial characterisation of Subcoal® to understand the key components. Then the thermal chemistry of Subcoal® has been studied using TGA in different gaseous environments (N2, air and CO2) to understand the kinetics of how this material might behave if injected at the bottom of a blast furnace. The data has been compared with coals supplied by Tata Steel. Then blends of Subcoal® and coal have been produced to study the thermal chemistry of mixtures of fossil fuel coal and non-fossil fuel Subcoal® and to understand if these sub-components react synergistically or antagonistically. As part of this work, the devolatilisation of coal was compared using drop tube furnace versus a horizontal tube furnace. The drop tube furnace closely mimicks the conditions in the raceway of a blast furnace. Finally, the thesis reports studies of the torrefaction or hydrothermal carbonisation of Subcoal® as potential methods to upgrade this material in terms of its potential use in ironmaking. This was the first time thermal treatment was done on Subcoal® samples. Thermal treatment was found to increase the reactivity of Subcoal® |
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| Keywords: |
thermogravimetric analysis, non-fossil fuels, torrefaction, kinetic analysis |
| College: |
Faculty of Science and Engineering |
| Funders: |
EPSRC doctoral training grant |