Under the deal, the logistics firm will transport up to 18 million tons of coal from BHP mines in the Mpumalanga province to the Richards Bay Coal Terminal.
The contract will increase Transnet’s capacity on the line to 81 million tons in the next seven years from the current 73 million tons.
The company said: "Take or pay contracts are crucial to Transnet’s capital investment program as they provide revenue certainty, a key consideration for raising funds in the capital markets.
"Take or pay contracts mean that Transnet commits to providing trains and a customer is obliged to pay whether they have product or not."
Transnet expects to finalize deals with 28 other coal firms by the end of November.
The exporters are expected to sign individual 10-year contracts starting from 1 April 2014 and ending on 31 March 2024.
