BHP takes a $2.3bn writedown on Jansen potash. The mine keeps getting more expensive.

BHP's Jansen potash project is becoming the mining industry's most expensive lesson in greenfield cost discipline. The company has flagged a $2.3 billion impairment and simultaneously disclosed that Stage 2 costs have risen from $4.9 billion to $6.9 billion, a 41% increase on an expansion that was only approved in 2023, as Morningstar's deal coverage confirms. Stage 1 tells the same story: approved at $5.7 billion in 2021, now sitting at $8.4 billion. BHP US shares fell about 2% on the news. The strategic rationale for Jansen, that potash provides diversification away from iron ore and long-term fertilizer demand exposure, has not changed. But the first production is still pencilled for mid-2027, and investors now have to ask whether the economics at $15 billion-plus of combined capital still justify the original thesis, especially if Jansen's supply volumes push global potash prices down by the estimated 7% some analysts project at full ramp.