Fate of the Residual Elementsfrom Coal Injection during Iron Making Processes

The key objectives / aims of the Research:
The primary aim of this project is to determine the specific reaction behaviour of volatile elements from coal injection in blast furnace ironmaking such as sulphur, potassium and sodium.

The main objectives will be to:
1. Develop a methodology to determine the qualitative and quantitative analysis of volatile elements and compounds produced in different thermal conditions and gas compositions.
2. Define the phases of the compounds that leave the different thermal zones and enter the process, identifying potential material interactions.
3. Determine the potential impact and mitigation of the phases identified on the blast furnace ironmaking process.
4. Identify how the blast furnace process influences the distribution and partitioning of sulphur, sodium and potassium compounds between the gas and solid phases.

Questions the project intends to answer:
Pulverised coal is injected into the blast furnace to decrease the specific coke consumption during the Ironmaking process. The impact of specific types of injection coal on the blast furnace performance is not well understood in terms of the sulphur and alkali metal compounds (known as 'residuals' in the process).
Since the coal trading market is very volatile due to the high demand and the limited availability of each mine, flexibility with regard to the selection of coals is of major importance. Based on regional differences in coals there is a wide variation in the physical and chemical properties. Understanding and selecting coal with these different characteristics, in regards to usage in ironmaking processes, is complex and requires further research in regard to residual elements that remain after coal combustion in the raceway.

The project will investigate what compounds are present and how they are affected by different thermal conditions and reacting environments. In the blast furnace these residuals are known as critical elements, which are believed to influence permeability of the 'deadman' region and 'cohesive zone'. This information will also considered in the context of the TATA Steel reduced CO2 alternative ironmaking process Hisarna, to establish how these residuals influence the surface reactivity of the raw materials and therefore the process stability. The understanding of the role of these residual elements in coal injection will be used to improve the selection of suitable coals for this purpose. Based on the results of the project, further selection criterion could be derived for coals with high amounts of residual elements based on gaseous modifications; preferable chemical reactions; solution reactions (HIsarna); or condensation areas (blast furnace).

The Novel Physical Sciences/Engineering methodology that will be carried out during the course of the project:
A drop tube furnace will be used to simulate the combustion 'raceway zone' of the blast furnace and adapted to develop a novel test methodology which can be used to measure the partitioning of residual elements between gas and solid phases. This information will aim to have an impact on the blast furnace process through improved selection of coals and potential process changes to mitigate against issues. Advanced analysis will be used to determine the effect on surface properties and relate to the novel low carbon alternative to blast furnace ironmaking, Hisarna.

The area in which the research aligns with EPSRC portfolio:
This work aligns to challenges in manufacturing and potential futures for these. Through improvements in blast furnace efficiency through the identification and selection of the most suitable coals, and by applying the findings to the alternative Hisarna ironmaking process, this work aligns to lower carbon manufacturing futures.