i doubt one can find a large enough SOP operation for RIO or another major, unless the East African projects (eg. DNK) can deliver their novel promises. for example, 400,000tpa hopefuls, such as RWD, are too small for RIO or BHP. SOP sells for a premium for good reason, namely, small supply. this is why BHP, for example, is investing in MoP in Canada
ELM probably has the lowest operating costs in the MoP sector, which is why it remains attractive