A Rio spokesperson told Mining Journal a contractor company had been impeding access to the site for the past week as part of an ongoing dispute with their employer.
The situation had led to the death of a member of the security staff on July 9, with the matter now under investigation by police.
"As safety is our highest priority, operations have been suspended since last Friday (July 6). We have been working with the contractor, community leaders and the regional government to try to resolve the issues as speedily as possible," he said in response to emailed questions.
A similar situation occurred in late March, when RBM had to declare force majeure on titanium dioxide products in April.
The National Union of Mineworkers said this week its members had been put on forced leave for an unknown period of time due to contractors blocking roads since July 6.
It called for the department of mineral resources to intervene before the situation deteriorated further.
NUM Kwazulu-Natal regional secretary Muzi Zakwe said the issues had nothing to do with NUM members, so they should not have to be put on statutory leave.
"This is not for the first time our members day's leave has been used in this manner since it happened in March this year. The employer must introduce a leave of the special kind known as community riot leave in order to avoid tapping into our members leave days," he said.
Meanwhile, broker SP Angel said the shutdown due to violent intimidation could force Rio to find new supply and suggested it might look to AIM-listed BlueJay Mining.
"Rio Tinto must surely want to ditch RBM and the trouble it causes … They had a project in Mozambique lined up, but the Riversdale disaster means they might not want to go back in there for another decade or two", it said.
"We reckon Rio's QIT business in Quebec needs cheap, high-grade feed to restore its fortunes with Bluejay Mining tempting management with its world-class grade and close location, albeit within the Arctic Circle."
SP Angel said buying Bluejay could help Rio "restore value so that it could offload the business in a rerun of the BHP flotation of South32 which was a win-win for both companies".
RBM produces 33% of global zircon supply and 25% of its high purity pig iron.
