Potash from a tour of the BHP Jansen Potash Mine. Photo taken in Jansen, Sask. on Wednesday, Dec 3, 2025. BHP Group will take a US$2.3 billion writedown on its giant Jansen potash mine, after announcing the latest in a series of cost and time overruns for an expansion of the project in Canada. Sign In or Create an Account BHP, the world’s largest miner, has routinely blown past cost estimates for the controversial project.