Using your figures, the equity provider would end up with about...

Using your figures, the equity provider would end up with about 75% of the company shares for the $250 million.

I'm also not sure if you are mixing up $US and $A. The announced CAPEX is A$850m odd (but likely considerably more funding will be needed) and the debt funding mandate, I think, is for US$600 million. 

I reckon the aim will be to give up about 30% of the company in return for the required equity funding. That might sound a bit fanciful from where we are at the moment, however the equity deal won't be concluded until debt finance, all permitting and the SMS turnkey price and production guarantee are locked and offtakes firmed up. The equity provider would be getting 30% of the A$4.7 billion NPV, i.e. around $1.4 billion, for the $250 million (your figure) which is still a pretty good deal for them. Anyway, a lot of water to go under the bridge yet and I can live in hope.