South Flank is BHP's proposed new development for replacement tonnes for the depleting Yandi deposit. Final investment approval has not been received but BHP has submitted environmental reports and indicated it is its preferred development site. The South Flank deposit is located immediately south of BHP's existing Mining Area C (MAC) mine in the Pilbara region of Western Australia, approximately 130 km north-west of the town of Newman and 8 km to the south of MAC. We estimate that it will produce 80 Mtpa at full capacity and have an average raw grade of 62% Fe and both lump and fines. With a total development cost of between US$2.4 billion and US$3.2 billion, or US$30-US$40 per tonne, it is intended to replace BHP's 80 Mtpa Yandi mine which will deplete by the mid 2020's. We assume that South Flank's ramp up will coincide with Yandi's depletion so that total tonnes produced by BHP remain steady on an annual basis.