I thought I might weigh-in on this topic as I have had some experience pumping cement slurries at 1895 kg/m3 and frac emulsions of similiar SG.

The science of slurry additives is not new. Earl P Halibuton started adding surfactants to slurries before I was born (not last night). A single 500 HP pump can push 1600 litres/minute through 2" line pipe at about 500 psi if I recollect accurately. More HP and a 3" line allow for rates and pressures that can fracture sedimentary rock. Pressure will be a limiting factor for NOT's slurry pipeline, but I can see a single pumping station working with friction reducers and fluid loss additives keeping the slurry moving. A 4" line seems small, but I'm sure that NOT has run the numbers.

Aafab