My point is your methodology is totally incorrect even allowing...

"yeah geology... identifying what's there. engineers do the mine planning, scheduling and financial feasibility."

Maybe you should research what is entailed in getting a Doctorate in Mining Geology, as distinct from Geology

Dr Anderson holds a BSc. (1st Class Honours in Mining Geology) and a PhD in Mining Geology, both from the Royal School of Mines, Imperial College, University of London.

My point is your methodology is totally incorrect even allowing for your range.

Processing & Mining of tailings is significantly cheaper than mining fresh rock or oxides from satellites then transporting & processing it thru the communition circuit.

Tailings only go thru the CIL circuit, ore from Viper/Pit5 goes through both circuits and includes much of the very expensive cut back.

You cannot work out the cost of processing tailings when the only figures you have to base your calculations on include Viper & Pit5.