I dont see adding future capacity to the HIO slurry line being a...

I dont see adding future capacity to the HIO slurry line being a possibility myself.
The pipe ID will be sized to a pre-determined flow rate for maximum wear life and also to take into account the settling velocity of the slurry. The faster the slurry is travelling the higher the wear rate., but if its too slow then it settles and blocks the pipe.
Adding extra capacity, without increasing the pipe ID will have to result in higher velocities and higher pipe line pressures.
So, the limiting factors will be the maximum velocity of the slurry and the pipeline maximum working pressure, both of which would be optimized for the best Capex/Opex outcome for the HIO project.
Just my two cents worth...
GLTA
MTC