Unit cost guidance for the FY2019 year is expected to balloon between $68 per tonne and $72/t as a result of an 8% increase in strip ratios, higher diesel prices, local inflationary pressures and an extensive maintenance program planned for the six months to December 2019.
Lower volumes from its Broadmeadow longwall mine and Blackwater open cut mine cost the company $263 million in FY2018.
"Operational conditions at Broadmeadow and Blackwater improved significantly in the June 2018 quarter," BHP said.
"In the medium term, we expect to lower our unit costs to approximately US$57 per tonne."
The Queensland coal unit reported revenues of $7.3 billion for FY2018, compared with $6.3 billion for the previous corresponding period and net costs of $2.8 billion compared to $2.3 billion previously.