BHP now expects the expansion of its Jansen potash mine in Canada to cost $6.9 billion and recorded a $2.3 billion writedown tied to the project.
The increase reflects another round of cost and schedule overruns at a mine BHP has repeatedly flagged as a key long-term growth project.
Jansen has already seen investment estimates rise and timelines slip, extending a pattern of setbacks at the world's largest miner's flagship push into potash.