Increase to Diavik ore reserves

06 March 2015

Increase to Diavik ore reserves

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To support the annual Mineral Resources and Ore Reserves review process detailed in Rio Tinto’s 2014 Annual report released today, Rio Tinto Diamonds has declared an increase of its Ore Reserves for the Diavik operation in Canada, resulting from the completion of studies and evaluations.

The update is reported under the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves, 2012 (JORC Code) and ASX Listing Rules, and provides a breakdown of the updated Mineral Resource and Ore Reserve in Table 1 and 2, and a summary of information to support the Ore Reserve increase in Appendix 1.

The update is based on a rigorous examination of the identified resources, mining options and operations planning for Diavik resulting in:

  • the addition of a new Open Pit mining development from the fourth kimberlite pipe, A21, to be mined with the existing underground production from the A154N, A154S and A418 pipes; and,
  • production from A21 which will bring open pit mining back into the mine plan, adding important incremental production to ongoing underground output to sustain the current total production rate over the existing mine life.

Diavik is a diamond mine operating at a secure remote site in the Northwest Territories, Canada. Access is by air year-round and a seasonal ice road is available for eight to ten weeks each year over which the mine’s annual re-supply of bulk materials and large cargo are transported.

The mine is a joint venture with Rio Tinto holding 60 per cent and serving as the operator and manager. The ownership structure and joint venture arrangements have remained unchanged since commercial production began in 2003.
The updated Ore Reserve and current mine plans indicate production continuing to 2023. Remaining mineral resources are available and are being evaluated, and may have potential to be added to the mine plan in due course.

Diavik’s fourth kimberlite pipe, A21, is located on the mine site near the other three pipes currently in production. During the fourth quarter of 2014, Rio Tinto approved a positive feasibility proposal to add A21 to the existing mine plan. An implementation team is in place and construction activities began immediately. Development includes site preparation, earthworks, water management and pre-production overburden stripping. First ore production from A21 is expected in 2018.