CAPE TOWN (Reuters) -A South African unit of mining giant Rio Tinto will seek board approvals next year to resume expansion plans at the mineral sands business halted in 2019 following rising insecurity and threats to its workers.

Richards Bay Minerals (RBM) plans to take the Zulti South project to the Rio Tinto board for approvals next year after updating feasibility studies, its managing director, Werner Duvenhage, said on Thursday.

Rio Tinto had paused the $463-million Zulti South expansion project in the KwaZulu-Natal province on the country's east coast.

The threats of violence are showing signs of waning and RBM is finalising feasibility studies for the project, which was initially expected to extend the life of the operations by 25 years, to resume, Duvenhage said.

The delays might mean that the investment required has also changed, he said

"The cost of Zulti South will change because time has passed so that's the part of the update of the study taking place at the moment," Duvenhage added.

Rio Tinto mines and processes heavy mineral sands at the South African unit, including ilmenite, to produce zircon, rutile, iron and slag.

The RBM unit, its only operation in the country, was beset by violence and community unrest between 2019 and 2022 forcing the company to suspend some operations and declare force majeure.

The company is now confident to take the project back to the parent company for approvals because the security situation is "good at the moment", Duvenhage told reporters in Cape Town, where RBM was announcing plans to buy 140 megawatts of renewable energy for the operations.

(Reporting by Wendell Roelf in Cape Town; Additional reporting by Felix Njini; Editing by Tannur Anders and Sriraj Kalluvila, Kirsten Donovan)