Hazer have always used a fluid bed reactor. It was only the...

Hazer have always used a fluid bed reactor. It was only the Mineral Resources reactor that used a different type, a paddle tube reactor using the Hazer process. The difference is that because the Hazer process can operate at relatively low temperatures, 800-900C. They thought they could get away with not having a refractory lining, but rather use a high temperature alloy. This is somewhat a shortcut which should save energy input. As demonstrated by the failure of the Chinese fabricated reactor, subsequent re-design and engineering by Hatch to create the Mk1 reactor and to be replaced now by a much larger and more conventional refractory lined reactor. The lining adds a lot more thermal mass, but lower thermal conductivity which probably means higher operating costs, but more stable temperature control with less fluctuation.
Although Glen claimed that the Mk2 reactor was "ready to rock and roll" and also repeated in the Hazer quarterly announcement we now know that it is only the steel reactor shell that is complete. Other components are still to be put together. This is presumably why they are now saying installation in 2025. When that will be is anyones guess. A year should be plenty.