BHP Group will record a $2.3 billion writedown on its Jansen potash mine in Saskatchewan after costs for the phase two expansion jumped to $6.9 billion, up from the previous $4.9 billion estimate. The company pushed forward with construction despite ongoing investor skepticism about the project's massive price tag.

BHP approved the mine in 2021 after years of internal debate, then greenlit phase two expansion in 2023 when fertilizer prices surged following Russia's invasion of Ukraine. However, prices have since retreated even as costs continue climbing at the controversial operation.

The Jansen project represents BHP's bet on potash as a major growth driver, potentially rivaling its Australian iron ore business over a century-long operational lifespan. Phase one production remains on track for next year, but phase two won't start until the end of 2031.

These repeated cost overruns underscore persistent execution challenges for BHP's potash ambitions, testing investor patience with a project that's already years behind schedule and billions over budget.