The 70 to 120m Mez is subordinate to the $190m already secured....

The 70 to 120m Mez is subordinate to the $190m already secured.
Correct. The mezzanine debt would be subordinate to senior debt by definition.

The Mez finance will be serviced from the 190m facility
No it won’t. That makes no sense.
My recollection from a previous announcement, was that the Kfw IPEX-bank loan can’t be drawn down until the other project finance had been spent.
Basically spend your first $108m from your other sources before we give you our $190m.
The terms of both senior and subordinate debt are/will be such that repayments are not required until the plant is up and running.

Thats why this type of debt needs approval also from the primary financier.
No for the same reason above. Doubt Kfw IPEX-bank need to formally approve any particular secondary lender as they are the primary, so always come first.
Kfw IPEX-bank needs to see that the company has raised all the equity required, including that any subordinate loan facilities are in place.

How long is the proposed plant going to take to construct?
2 years. Hopefully commencement in Q3 2018. First production Q1 2020.