Micro-CT based characterisation of the IMDC-RMDC interfacial interaction in blends of Australian and international coals

The key aim of this project was to characterise the IMDC-RMDC interface quality for a range of interactions between different coals, using a quantitative measure from 3D non-destructive micro-CT images. The measure used is the excess porosity, which is large when there are high porosity zones in the vicinity of the IMDC-RMDC interface, and small when there is little difference between the porosity near the interface and the porosity in the bulk of the RMDC. This appears to be a robust and accurate means of quantifying the quality of the IMDC-RMDC interface.

Methodology was used to examine IMDC-RMDC interactions over a set of coals from a commercial operation, being that of Tata Steel Europe, who participated in the project. This allowed for investigation of a range of coals, of both Australian and international origin.

A secondary aim of the project was to examine use of a non-destructive method for characterising the chemical properties of surfaces of inertinite particles before coking using FTIR spectroscopy. While this technique shows promise, difficulties were experienced associated with obtaining good signals from uneven surfaces of the particles, as well as issues with evaluation of the resulting spectra.

Results showed that, in general, good IMDC-RMDC bonding occurred for 4 of the 5 vitrinite sources used in the study. For the other vitrinite source, called Coal U here, poor bonding occurred between the RMDC and IMDC for certain coals, as measured by the excess porosity.

Evidence of a link between the internal porosity of IMDC particles and the excess porosity, at least for IMDC particles that were carbon dominant (as opposed to being mineral infused) was found.