Your rail capex costs of ~ $5/km for the Pilbara are factually correct, whereas SDLs much lower estimated capex costs in an area of the world where there is no benchamrk are aspirational targets. That isn't a like for like comparison - it is a huge risk that the capex for developing of SDLs resource is massively understated especially with a much longer rail length than the Pilbara
Yes, labour cost in Western Africa will be significantly lower - but on SDLs own chart, SDL will be a third cost quartile producer for the vast bulk of its production. Materials (steel etc), will be at global rates, higher once greater freight and inland transports are added. And there are no free carries in the Pilbara.
SDL Price at posting:
32.0¢ Sentiment: None Disclosure: Not Held