Coal Preparation » Fine Coal
This project has investigated the use of micro-CT to provide a 3D particle analysis focussed on petrographic components. The technique was specifically calibrated on broad coal maceral groups and general mineral content. A unique image analysis program was then developed to output 3D particle surface composition- a characterisation tool targeted for coal flotation processes.
Site A industrial flotation samples
The project used a pre-existing suite of industrial flotation samples from project C33055 to adjust the system to finer particle size and test the analytical concepts. It was observed that maceral content varied dramatically within the sieved size fractions.
Laboratory Denver Cell study
The Site A flotation feed sample was also used in a laboratory Denver cell to provide an indication of maceral variation during typical testing. There was clear differences between selected samples before and after collector addition; notably that the sample with collector addition had a higher purity of vitrinite grade.
Site B Industrial flotation samples
A final test of the project was conducted on a second suite of industrial flotation samples derived from two cells in series (ie feed / product / secondary product / tailings). Theses samples proved to be technically challenging for micro-CT analysis due to the presence of high-density minerals interacting with the X-ray.
Exploring the data sets through the particle grade distributions provided unique and significant insight into the performance of industrial and laboratory flotation cells. Combining the surface volume data sets allowed a “Yield-Maceral” curve to be constructed from the feed sample based on removing surface vitrinite from high to low purity. This provided an ability to indicate product petrographic quality for different yields with the need for laboratory lab testing.
Two prospective improvements were successfully trialled during the project. The first utilised a 3D printed sample holder for the micro-CT sample auto-changer; allowing for automated analysis with standardised sample presentation. The second was the use of the XCT beam line at the Australian Synchrotron to scan coal particles at resolutions of 0.375um/vx. It was found that these scans could be digitally transferred to the UON micro-CT computer for further image analysis.