ZEN just hired someone to overlook their metallurgical testing. RPA stated in the PEA:

"The metallurgical testing to date has focused on achieving purity and not on optimization of the process. Further improvements in process design, performance, and cost estimation are to be expected with advanced levels of study.

Ore samples for metallurgical testwork should be representative of the ore blend for each year in the LOM plan. The metallurgical complexity of the deposit has been evaluated using two composit samples (East Pipe and West Pipe) for flotation testing, and using East Pipe composite material for purification testing.

Ore variability needs to be investigated through mineralogical analysis and flotation testing."

http://www.zenyatta.ca/upload/documents/2248-rpa-zenyatta-albany-pea-ni-43-101-r.pdf

The process has not been optimized. It may have been improved, but apparently not to the level where there is comfort in bulk testing and starting the PFS.