Yes the mining cost is very low , but the processing cost both...

Yes the mining cost is very low , but the processing cost both CAPEX and OPEX are very high hence the low payback of around 4 to 5 years or an IRR of around 22%.
Easy to compare with expensive HPAL needing expensive titanium autoclaves , but why ? considering they have proven this ore is amenable to what is anecdotally a cheaper process route with heap leaching and they use as a selling point .

I suspect punters feel AXN need to work on getting both the CAPEX and process cost down , considering half the OPEX work is done ie crushing is negligible in cost on a 2.4 mtpa plant , and they are processing a pregnant liquid, $700M seems about 300% higher than a simple CIL gold plant of a similar mtpa that has a mill grinding ore to microns in size .