DAR ES SALAAM, Oct. 12 -- As competition for Africas minerals intensifies, Tanzania faces another major challenge: how to negotiate mining agreements that protect national interests over decades, rather than focusing only on immediate investment and export revenues.

The question is particularly important because mining contracts can determine who controls production, where minerals are processed, how much revenue governments receive and how much economic activity remains in local communities.

Across Africa, governments have increasingly sought to renegotiate mining arrangements and strengthen local participation.

Guineas Simandou iron-ore project illustrates both the scale of the opportunity and the importance of transparent agreements...