Exploration company Bowen Coking Coal (ASX: BCB) has reported a 3.5 million tonne increase to the mineral resource estimate at its Isaac River coking coal project in central Queensland following results of a six-hole maiden drilling program earlier this year.
The project’s total coal resource estimate now stands at 8.7Mt – up 67% from the previously reported estimate of 5.2Mt.
Approximately 8.35Mt of the new figure has been classified as measured and indicated and represents over 95% of the total resource.
Vermont Upper seam
Bowen managing director Gerhard Redelinghuys confirmed the higher-quality Vermont Upper seam – intersected in all drillholes – contains an estimated 3.2Mt, of which 89% is classified as measured and indicated.
“The primary purpose of our drilling was to test the expected existence of Vermont Upper, which produces a better-quality coking coal in the region and we have achieved that in all six holes,” he said.
“The raw quality analysis we have received to date is very pleasing, and we hope the washability data will confirm the coal quality at Isaac River is better than expected when compared to the historical data.”
Washability tests are designed to test coal qualities and yields at different densities to assist in determining the optimum beneficiation strategy to ensure maximum value release from the raw coal.
The information is used to analyse the characteristics and quality of a final coal product which will ultimately impact placement and pricing in the market.
Bowen has engaged Xenith Consulting to manage the washability tests and coal quality analysis process for the remainder of the Isaac River program in conjunction with McMahon Coal Quality Resources at a laboratory in Mackay.
In July, Bowen reported raw quality coal data from two of the maiden drillholes at Isaac River held good production potential for the project, located east of BHP Mitsubishi Alliance’s Daunia open cut mine in the Bowen Basin.
Results showed the previously-untested Vermont Upper seam to have “very good coking coal characteristics”, with a high crucible swelling number (or CSN) capable of producing a low-ash coking coal.
CSNs are regarded as a key determinant to confirming a coal seam’s coking ability.
As Bowen had predicted, the lower section of the deposit’s thick Leichhardt seam demonstrated significantly better coal properties than the top section.
“[Our predictions] support the view that this primary target was most likely undervalued in previous studies,” said Mr Redelinghuys said at the time.