So ~58% in silver metal goes to the smelters. Not a very good deal. NCZ should renegotiate that ASAP.
So I estimate the total value of the silver from the tailings deposit to be around AUD$780 million (30 million ounces x AUD$26 ounce). We take away ~58% to the smelters = AUD$327.6 million
Smelter 80% payable on AUD$327.6 million = AUD$262.08 million
Take away $7.64 million (USD$5 million) primary debt facility for Varde = AUD$254.44 million
Say we make the assumption of even production for 6 years to simplify the exercise = AUD$42.41 million per year from silver production
Now we give the 10% for 4 years back to Varde for additional debt facility = (42.41 x 10%) x 4 years = AUD$16.96 million
So now we go back to the AUD$254.44 million and subtract the AUD$16.96 million = AUD$237.48 million
Silver payment worth ~AUD$237.48 million for the life of the tailings deposit after deducting the smelter and finance arrangements.
And NCZ still have another 20 million ounces of silver in the In-situ deposits that are indicated and inferred.