Global miner Rio Tinto has approved the $463 million construction of the Zulti South project in South Africa, a move it says will extend the presence of its majority-owned Richards Bay Minerals in the country.
The mine extension - for which Rio Tinto will contribute $343 million - will help RBM maintain its output of high-margin zircon and rutile in the face of a declining orebody grade at the company's existing Zulti North lease area.
Construction on Zulti South is scheduled to start in mid-2019, subject to the granting of all necessary permits, with first commercial production expected in late 2021.
RBM is South Africa's largest mineral sands producer and currently operates four mines in the Zulti North lease area, a mineral separation plant and smelting facility.
Rio Tinto, which has owned 74 per cent of the company since 2012, said the Zulti South investment will be fully self-funded from RBM's cashflows.
"Rio Tinto has a long history in South Africa, and today's investment underscores our commitment for the coming decades and beyond," Rio chief executive Jean-Sebastien Jacques said on Tuesday.
"Zulti South is one of the best undeveloped minerals sand deposits in the industry, and will significantly extend RBM's position as a world-class, first-quartile asset."
Shares in Rio Tinto were last trading at $101.48 on the ASX, a near 11-year high, and up nearly 30 per cent for the calendar year against a backdrop of rising iron ore and copper prices.