Document Type

Conference Paper

Publication Date


Publication Details

This conference paper was originally published as Calleja, J, Rapid Rating Using Coal Mine Roof Rating to Provide Rapid Mine Roof Characterisation from Exploration Drilling, in Aziz, N (ed), Coal 2006: Coal Operators' Conference, University of Wollongong & the Australasian Institute of Mining and Metallurgy, 2006, 20-27.


The Australian coal industry is currently experiencing rapid expansion with many companies fast tracking the development of new mines. In many cases, operators are collecting large quantities of exploration drilling data for pre-feasibility and feasibility studies as well as for operational start-up and mine expansion. “Rapid Rating” is a new method for calculating the Coal Mine Roof Rating (CMRR). It has been designed to allow large quantities of exploration data to be processed quickly to provide a standardised indicator of geotechnical conditions. It is intended to make CMRR more readily available to mine operators. When the CMRR was first developed there was less core drilling conducted in the USA than is conducted in Australia today. So it was specifically designed to allow geotechnical information to be collected easily in the absence of core data. It was then modified to allow calculation from core. The method for calculating CMRR required a geologist to collect the inputs manually, and this may take between 1 – 4 hrs. The need to assess large quantities of drill core in very short time frames has only emerged relatively recently, and “Rapid Rating” has been developed to meet this need. “Rapid Rating” can calculate a CMRR from between 40 minutes and 5 minutes for a large data set. It can calculate CMRR over numerous possible bolt lengths for sensitivity studies on different bolting horizons and during the early stages of mine design when bolt length is still a variable. The “Rapid Rating” calculation method is automated which makes the results more repeatable and less subjective. The “Rapid Rating” system, is described, which explores the benefits and limitations of this technique for mine design and strata management.