A plan to build Zimbabwe’s biggest platinum mine at a cost of about $4-billion is floundering because a military stake in the project has deterred potential backers, according to people familiar with the funding discussions. The African Export-Import Bank has the mandate to raise money for the mine, a joint venture between Russian and Zimbabwean investors. While the bank provided $192-million of its own funds, meetings in the past year with investors including South Africa’s Public Investment Corporation, the continent’s biggest fund manager, failed to bring additional commitments, one of the people said, asking not to be identified because the talks are private.