Whitehaven has given FY2019 production costs guidance of $67/t for the year.
Record profits from Australia's miners making economy stronger.
Output reaches highest level in 21 years.
Yancoal's tier-one assets drove continued transformational growth.
The mines are the backbone of the company's metallurgical coal business.
For the six months to December, production from the underground longwall operations was 27% higher.
BHP said it expected to lower its unit costs to about $57/t.
Narrabri's longwall change-out took place entirely during the September quarter.
Australian coking coal production of 7.5Mt was 23% higher than in 2017.
Wollongong Coal expects the miner to be recommissioned in the panel by end of February.
Mining will continue in the second panel until mid-March.
Solid Lihir performance also gave company a boost.
It can be run from any load haul dumper
Anglo American's metallurgical coal production for the December quarter increased by 15% to 5.6Mt.
Mill Recovery Enhancement Project continuing to come on line.
Higher gold price giving company more options.
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