$12k is to make HPA from aluminium metal, which is the incumbent...

$12k is to make HPA from aluminium metal, which is the incumbent way, which is what Sumitomo does.
However, the new methods that Chem X and Alpha are pursuing are much cheaper than $12k.

I wouldn't believe too much in the IPT scoping study 4k figure. The small print did caveat a possible variance of 30% in that report.
Although maybe they can, I'd be surprised if they could accomplish that price and cater to high-tech chemical applications. Perhaps they are looking for a cost-effective alternative in less demanding industrial applications.