The opencut mine current produces 4.8 million tonnes per annum of ROM coal but will expand to an 8Mtpa operation by the second half of the 2009 calendar year.
The investment will be made to develop the Klipspruit project which will include a 16Mtpa processing plant onsite.
The plant, named the Phola Coal Processing Plant, is a 50:50 joint venture with Anglo Coal and will replace the Rietspruit coal washing plant, located about 32km from the Klipspruit site.
Each company will utilise half of the processing plant's capacity and 4Mtpa of the coal mined for Klipspruit will be exported through the Richards Bay Coal Terminal.
The total mine life for the Klipspruit operation is about 20 years at the boosted production rate based on current reserves.
The mine is operated by BHP Billiton subsidiary Energy Coal.