Ann: Ohmgebirge study evidences world-class potash development, page-98

You might also note ( if you even bother reading SHP anns ) that US$620m is approx AUD$1B

You might also note the fob price is almost half for jansen compared to this study ( not including by products ).

"BHP's capex is more than double SHP's on per Mt basis."

Jansen isnt really comparable in any way to this study its a tier 1 generational asset. Jansen is sinking a shaft that will end of having multiple stages and production levels with various outputs. The capex is frontloaded because bhp can finance it & its going to be required in the near future.