Ann: High Grade Gold Results from the Morila Super Pit, page-46

Your figures don't make any sense whatsoever

You're using the 326kt of Tailings mined
But then use the 798kt & 846kt of total ore mined/processed to work out a cost of mining.

The 798/846 includes Pit 5 & Viper which is far more expensive to mine & process.
The Tailings only go through the CIL circuit, require no crushing or grinding.
The Pit5/Viper ore is more expensive to mine/process, but does have better recoveries.

If you read the asx Tailings costing announcement I mentioned, you'd see Tailings recovery is not 75% as you state.