Changes to Mineral Resources and Ore Reserves

RNS Number : 2960Y

Rio Tinto PLC

02 March 2017

 

Changes to Mineral Resources and Ore Reserves

2 March 2017

On 2 March 2017 Rio Tinto announced to the Australian Securities Exchange (ASX):

·      increases in Ore Reserves and Mineral Resources in Pilbara iron ore deposits in Western Australia;

·      increases in Mineral Resources for Rio Tinto's 100 per cent-owned Jadar Lithium and Borates Mineral Project in Jadar, Serbia;

·      a decrease in Mineral Resources at Rio Tinto's 59 per cent-owned Iron Ore Company of Canada (IOC) mine in Labrador City, Labrador and Newfoundland, Canada; and

·      a decrease in Mineral Resources at Rio Tinto's 100 per cent-owned Argyle Diamond mine in the East Kimberley, Western Australia. 

These announcements were made in accordance with Chapter Five of the ASX Listing Rules and the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves, 2012 (JORC Code).

Copies of the announcements are available on Rio Tinto's website at riotinto.com/mediareleases 

During 2016, increases to estimated Pilbara iron Ore Reserves have been delivered as part of the ongoing resource development drilling program designed to maintain Ore Reserves coverage ahead of mining depletion rates. Increases in Ore Reserves are reported for:

·      Hope Downs 1, which have increased from 196 Mt to 238 Mt due to the addition of the Hope Downs 1 South West mine area. The percentage of Proved Ore has increased significantly (from 3 Mt to 115 Mt) due to classification changes at Hope Downs 1 North.

·      Koodaideri, which have increased from 452 Mt to 594 Mt due to new Ore Reserves at Koodaideri 38 West / 21 West following additional drilling (more than 1,000 drill holes) used to update the geological model, Mineral Resource estimate, and increase the Resource classification to Indicated (in part).

In aggregate, estimated Pilbara iron Ore Reserves increased by 57 Mt during 2016 as set out below:

	Dry Product (Mt)
2015 Ore Reserves	3,458
Hope Downs 1 South West increases	42
Koodaideri 38 West increases	142
Net amount of other changes (including depletions of 305 Mt due to production and minor increases)	-127
2016 Ore Reserves	3,515

During the same period, estimated Pilbara iron ore Mineral Resources increased by 350 Mt. Increases in Mineral Resources are reported for:

·      Hope Downs JV Brockman, which have increased (from 571 Mt to 645 Mt) and Brockman Process Ore Mineral Resources have increased (from 348 Mt to 398 Mt) due to significant additions at Hope Downs 1 Bedded Hilltop; and

·      Hope Downs JV Marra Mamba, which have increased (from 396 Mt to 439 Mt despite transfers to Ore Reserves) and Detritals Mineral Resources have increased (from 70 Mt to 96 Mt) due to significant additions at Hope Downs 2.

During 2016, Mineral Resources at the Lithium and Borates Mineral Project in Jadar have increased by 19 Mt from 117 Mt to 136 Mt, a 16 per cent increase, including the first release of Indicated category Mineral Resources.  The updated Mineral Resource estimate comprises:

·      Indicated Resource:              52.4 Mt @ 1.79% Li₂O, 19.2% B₂O₃

·      Inferred Resource:                83.3 Mt @ 1.90% Li₂O, 13.0% B₂O₃

·      Total Mineral Resource:       135.7 Mt @ 1.86% Li₂O, 15.4% B₂O₃

During 2016, IOC Mineral Resources have decreased by 674 Mt from 2,762 Mt in 2015 to 2,088 Mt, a 24 per cent decrease.  This change follows both technical and financial reassessment of the Mineral Resources and does not impact IOC's Ore Reserves.  The current life of mine plan anticipates a production life extending to 2042, based on the reported Ore Reserves only.

During 2016, estimated Argyle Mineral Resources decreased by 29 Mt from 44Mt to 15 Mt.  Previously reported Mineral Resources included mineralisation that could support a potential extension of the currently planned mine life.  As mine life extension options are under ongoing review, the reported Mineral Resources have now been restricted to those parts of the mineralisation which can be potentially developed, mined and processed during the existing mine-life defined by the current underground operation.  It is for this reason that there has been a material reduction in reported Mineral Resources in 2016.

Mineral Resources and Ore Reserves are quoted on a 100 per cent basis.  Mineral Resources are reported exclusive of Ore Reserves.

 

Contacts

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