Askaf is an iron ore prospect in Mauritania.
Railway
The deposit straddles the SNIM railway 598 km from its port of export.
In 2014, Glencore Xstrata paid $1b to SNIM for access to that company's rail and port infrastructure. There will be branch lines to new mines at Askaf and El Aouj.
It is cheaper for Glencore to pay to share existing infrastructure, that to build its own, which would be wasteful, in a "beggar thy neighbour" way. The key factor is determining the price.
References
Askaf Wikipedia(Text) CC BY-SA