Digital Petrography® is a new, completely automated method of
coal petrographic analysis. Image-mapping of a coal sample using a digital camera produces a unique Reflectance Profile, which is the "fingerprint" of a coal. Interpretation
of the Reflectance Profile involves replication of the reflectance-distribution
by mathematical modelling, from which petrographic data are then inferred.
Digital Petrography® runs on Microsoft's Windows® NT operating
system. A typical screen during data collection, is shown at top right. The video-image
of the most-recently-captured CCD image, is updated every 1.3 seconds, until the pellet
has been covered. The blue area of this image is low-reflecting binder
between the several coal grains. Threshold segmentation is selected
using the horizontal bar-scale located under the image. To the right of the
video image, a cumulative Reflectance Profile of the coal sample is displayed.
A numerical model of coal is computer-adjusted to replicate the reflectance
profile of the coal, and the principal petrographic characteristics of the
coal are inferred from the model. These include Mean Random Reflectance,
Mean Maximum Reflectance, Percentage of Vitrinite, Percentage Reactive
Semifusinite, Percentage of Inertinite, and Total Inerts.
There are two other unique features of this software. A virtual reflectance
profile of any coal can be designed on the basis of petrographic parameters
Romax, and Total Inerts, for comparison with a scanned reflectance profile.
Secondly, the proportions of component coals in a blend can be determined
to +/- 2% (given that there is separation between component Romax peaks).
Digipet is the first non-human to have received
ICCP Accreditation in the competency exercise run by the ICCP, and it did so with superior Z-scores.
