Perret, Yes that is what I heard also but to be frank, I thought...

Perret,
Yes that is what I heard also but to be frank, I thought it was just a Pipe Dream. However, it looks like it is a reality. Same Chinese Mob that are underground mining at Kotabaru, Pulau Laut, South Kalimantan.
I know the geology of that area as I was CHPP Manager for Arutmin at Senakin, Satui and Petangas. We mined PCI/Thermal Coal and washed to 9 to 12% ash.
Compare that to unwashed PCI from BBM at about 5% ash and massive calorific value.
The Underground area in BBM is most probably high value HCC as it is further away from the ancient volcano that converted Pits 1 & 2 to PCI/Semi Anthracite and BBM West to Super PCI/Anthracite, but left Pits 3 & 4 as low volatile Hard Coking Coal/HCC. The underground area is further away again and TBAR further away again.
IMO DYOR