my ammended CLA valuation, page-48

I don't think your numbers are too far off actually.
AML had $A95m for 600ktpa plant (they are now planning bigger). Their numbers seem pretty similar to CLA given they are sulphide also, worth looking at.
As we know the laterite plays are much higher for plant etc.

So I would be guessing $A150-200m for a 1-1.5mtpa plant although I imagine costs in Namibia would be lower due to labor etc.
Would be good to put together sulphide plays chart with size and plant cost estimation (excluding digging it out of ground as depends on depth etc).

I guess it all depends on LOM (life of mine), how much resource can ultimately be found and total overall capex/opex to dig it all out of the ground as well given some underground digging might be involved.

Re 2mtpa for cobalt to be honest I have been looking I haven't found many?

As I'd noted they have just built a lithium processing plant at walvis bay so depends where you want to build your plant to get to the final product as well.