20m AUD is already taking into the account the 60% JV. LOM EBITDA is 25.4m USD, 60% of that and a 0.75FX rate gives 20.3m AUD. But you are correct on the Zn price.
AHK Ark Mines inks 1.5Bt Exploration Target for Sandy Mitchell REE play including NdPr; PFS due in Q4