I don't believe there is the indication that an air classifier...

I don't believe there is the indication that an air classifier will be required in the circuit schematic ZEO tabled to process high-grade c. 90% kaolinite raw ore in preparation for milling and roasting. My assumption is that simple dry screening will suffice, as such this component of the total capex will not be anywhere near the scale you have suggested. Although a fancy European high-end flash calciner capable of say 100-200kT pa I would assume would be in the vicinity of $20-30m.

No one is suggesting that metakaolin would be less expensive than a waste by-product from coal combustion (CCP) or fly ash, but its is known that the majority of coal fly ash is actually stored in ponds and once dry stockpiles diminish, there is an energy cost & logistic consideration to dry and transport.

So yes, of course CCP is less expensive than metakaolin, although the part that remains silent in your response, albeit I mentioned above, is that studies indicate that the max CCP that can be added as a binder in the blend to reduce cement component before the integrity of the concrete is compromised, is no more than 10% and at best 20% from what I've read, whereas you can go to 40-50% metakaolin binder and a concretes properties actually improve, not diminish and you achieve correlating % reduction in the carbon emissions, without new technology, in a simple way, you achieve a 40-50% reduction in concrete carbon emissions. More importantly, the transition to 30-50% metakaolin binder blends is already happening in Europe and North America, so I cannot imagine (with majority of Australian cement players subsidiaries of European parents) that it won't happen here in Australia - more a case of when not if, IMHO.

What is required is a high reactivity metakaolin (HRM) that lands at a price point that makes it compelling enough to facilitate fast-track adoption, by the domestic cement/concrete industry.

Simply saying its more expensive than fly ash is only one consideration, albeit an important one.