@reiners only because you asked. Based on actual quotes and tenders. Pareto did their due diligence and it has checked out.
In the latest corporate presentation, you'll see even after early site works were complete the allowance for CAPEX did slightly increase.
Certain aspects are easily explainable.
If GPX are aiming for 50,000tpa output and there feed in is 10% TGC, They essentially need to move and process 500,000Tpa.
If WKT are aiming for 40,000tpa output and there feed in is 17.9% TGC, They essentially need to move and process 224,000tpa.
That is less than half the ore moved and processed hence less than half the Capex.
Let's not forget that in order to preserve flake size, the processes of separation of flakes needs to occur. I'm no plant design expert however I would expect a lower TGC operation to require additional components and separation stages as to preserve flake size. Perhaps some of it comes down to contracts negotiated, as WKTs plant EPC partner is also a shareholder, they may be offering a better deal.
Only because you asked....
