The fate of residual sulphur from coal injection during ironmaking processes

Davies-Smith, Chay 2023. The fate of residual sulphur from coal injection during ironmaking processes. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Coal injection is utilised in modern blast furnaces as a method of reducing the consumption of coke, the production of which is expensive and energy intensive. Sulphur is an impurity introduced into the blast furnace predominantly from the use of coke and coal. High levels of sulphur in steel can lead to increased brittleness in a heated state. However, removal of hot metal sulphur reduces the yield and incurs additional costs. This study identified the routes through which sulphur from coal injection leaves the furnace and whether coal or process parameters can affect this. A drop tube furnace was used to study the volatilisation of coal sulphur from four blast furnace injection coals. The greatest contributing factor to the volatilisation of coal sulphur was the burnout of the char. H2S was measured as the major gaseous sulphur product during the partial combustion of the coal in the drop tube furnace. The use of alternative solid fuels in a coal blend was shown to affect the char burnout and sulphur volatilisation in the drop tube furnace. The addition of H2 and CO2 to the gas atmosphere of the drop tube furnace was shown to affect the char burnout and sulphur volatilisation of the injected coals. The relative sulphur fixation capacities of blast furnace charge materials across a temperature range of 150-900◦C were studied using a synthetic blast furnace top gas containing 500 ppm of H2S. The charged materials were shown to partially fix the gaseous sulphur, with fixation occurring predominantly at higher temperatures. The raceway was suggested as the primary source of volatilised sulphur in the top gas. The increased volatilisation of blast furnace sulphur was shown to be beneficial for the lowering of the sulphur load of the furnace, which in turn can facilitate a reduction of the coke rate.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	1). Coal injection 2). Ironmaking 3). Drop tube furnace 4). Sulphur 5). Biomass 6). Combustion
Funders:	EPSRC
Date of First Compliant Deposit:	22 November 2023
Last Modified:	22 Nov 2023 15:37
URI:	https://orca.cardiff.ac.uk/id/eprint/164128

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