They have been talking about this for years. I looked at it in the noughties. There were existing railways in Guinea totally unsuited to ore trains but the gummint wanted the ore line to serve what towns there are along the route. It is not easy country to build a railway, most of the route is through unmapped jungle. The mine is on the border with Liberia and there is a suitable track bed to the coast but Guinea for some reason would rather not use it. The mine is potentially huge but getting the ore to port, building a suitable port for huge ore carriers and African politics all have to be dealt with before you spend on detailed surveys. I am sure China would finance, build and buy the ore using its own labour and Guinea and Liberia would be no better off.
There is an Australian presence.
Twiggy Forrest of Fortesque Metals submitted a tender for the project but missed out to an international consortium. The glacier seems to be starting to melt.
The project is huge, the only disadvantage is the longer distance to East Asian markets, compared to NW Western Australia.
A more modest iron ore project, by Sundance Resources (of Australia), in Cameroon, is moving glacially. There are other iron ore projects in Africa as well.
If Guinea wants to keep the 650km line wholey within its territory, then this facilitates extension of that line into other parts of Guinea, and other countries such as Mali as well. Its international boundaries are in the wrong places for an efficient Guinean Railway.
There is a grand plan for the "African Integrated High Speed Railway Network" or "AIHSRN" for short. At least the new Guinea line and the AIHSRN are both standard gauge. Metre gauge in Guinea is mostly obsolete and even out of service.