Your maths is a bit wonky on several levels. Firstly COK coal is...

Your maths is a bit wonky on several levels. Firstly COK coal is not coking coal but PCI coal - which sells for quite a bit less. Also BHP for one does not expect the current spike in prices to continue. On the other hand current prices for coking coal are close to $US300 per tonne - an amazing $A400.

So, let's assume that in 2018 the mine does sell 2 million tonnes at $A250 per tonne. Thats $A500 million of gross revenue.

There are currently about 77 billion shares in COK. $500 million divided by 77 billion = 0.65 cents per share.
After consolidation of 500 to 1, there will be 154 million shares. $500 million divided by 154 million = $3.46 per share.
Given these numbers and the risks involved, it seems to me that a reasonable value for consolidated COK shares at the current time would be $1.50 (or about 0.3 cents each for the old unconsolidated shares).

It will be interesting to see what the market says.