The company will apply Florida, US-based K-Technologies' separation method in its Phalaborwa rare earths project in South Africa.

The backing of the federal environment minister is described by advocates as a betrayal.

The country's tax authority is asking Rio to pay $277m related to a 2015 borrowing used to pay an intragroup dividend.

Researches at the University of Waterloo found that catastrophic tailings flows have happened once every two to three years since 1965.