You can try the magnetic separation. Magnetic susceptibility of ferrite is much larger than that of hematite. Thus the ferrite particles to be adhered to a permanent magnet as opposed to hematite.

Magnetic separation seems the best option

I think you must use wet way (due to particle diameter) of magnetic separation at the field max. up to 0.1T (similar to ferrite-based permanent magnets). The gap between separator poles would be filled by steel wool.

Btw it is not clear if hematite is different in grain size from obtained ferrite nanoparticles. If hematite is much coarser you can use filtration through wide mesh filter paper...  

Generally, I think that only wet way will be effective and successful.