REG - Rio Tinto - Changes to Ore Reserves and Mineral Resources

Rio TintoAnnouncement

23/02/2022 07:00

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RNS Number : 5393C  Rio Tinto PLC  23 February 2022

 23 February 2022

 

Changes to Ore Reserves and Mineral Resources

Rio Tinto today announced to the Australian Securities Exchange (ASX) changes
to the following estimates of Ore Reserves and Mineral Resources compared to
those published in the 2020 Rio Tinto Annual Report:

·      Mineral Resources at Rio Tinto's Winu project in Western
Australia;

·      Ore Reserves and Mineral Resources at Rio Tinto Aluminium (RTA)
Pacific Operations at Weipa; and

·      Ore Reserves and Mineral Resources at Rio Tinto's Jadar project
in Serbia.

The updated estimates will be included in Rio Tinto's 2021 Annual Report which
will be released to the market on 24 February 2022.  Today's announcements to
the ASX were made in accordance with the Australasian Code for Reporting of
Exploration Results, Mineral Resources and Ore Reserves, 2012 (JORC Code) and
the ASX Listing Rules. Mineral Resources are reported in addition to Ore
Reserves. Mineral Resources and Ore Reserves are quoted on a 100 per cent
basis.

Rio Tinto's Mineral Resources and Ore Reserves as at 31 December 2021, and Rio
Tinto's interests, will be set out in full in its 2021 Annual Report.

Copies of each of the full releases to the ASX are available on Rio Tinto's
website at Resources & reserves (riotinto.com)
(https://www.riotinto.com/invest/financial-news-performance/resources-and-reserves)
.

Winu Mineral Resources

The updated estimates of Mineral Resources at Winu are supported by a
substantial increase in drilling information acquired since the release of the
initial Inferred Mineral Resource dated 28 July 2020, and on the advancement
of mining and processing studies.  These estimates comprise an Indicated
Mineral Resource of 249 Mt at 0.45% copper, 0.33 g/t gold and 2.72 g/t silver,
and an Inferred Mineral Resource of 358 Mt at 0.37% copper, 0.28 g/t gold and
1.95 g/t silver, giving a total Mineral Resource of 608 Mt at 0.40% copper,
0.30 g/t gold and 2.26 g/t silver, or 0.49% copper equivalent, at 0.2% copper
equivalent cut-off. This represents a 21% increase in tonnage, a 16% increase
in copper grade, a 12% increase in gold grade, a 40% increase in contained
copper metal and a 35% increase in contained gold metal.

Rio Tinto further reports that:

·      contained copper metal in the total Mineral Resource has
increased 40%; and

·      the Winu deposit is still open in several directions with
drilling programs in 2022 continuing to target extensions.

A proportion of the total Resource meets the requirements for Indicated
Mineral Resources and an Indicated Mineral Resource is reported for the first
time.

Since the initial public release of Mineral Resources, drilling targeting Winu
mineralisation has continued, resulting in an 83% increase in reverse
circulation drilled metres, a 93% increase in diamond drill metres, for an
overall increase of 88% drill metres.

The deposit remains open at depth as well as to the north, south and east and
the project team continues to explore the deposit margins. While exploration
activity has been somewhat constrained by site clearances at surface, the
presence of copper, gold and silver mineralisation of a similar geological
style and setting at the margins indicates that the Winu deposit is not, at
this time, limited by geology.  Further work is required to confirm and
increase understanding of extensions to the orebody.

In 2021 the project transitioned from Rio Tinto Exploration to Rio Tinto
Copper where it will be advanced through the next phase of delivery. Recent
technical and commercial reviews, independent of the study team, were positive
and the project continues to enjoy support from the Rio Tinto Board which has
approved additional expenditure to progress early works at Winu and further
prepare the project for a final investment decision.

The Winu project team continues to work with local Nyangumarta and Martu
Traditional Owners and regulators to progress the agreements and approvals
required for any future development.

Supporting information for the update to the Winu Mineral Resource estimate is
set out in the release to the ASX dated 23 February 2022 "Rio Tinto reports
first Indicated Mineral Resource and 40% increase in contained copper at Winu
project".

Weipa Ore Reserves and Mineral Resources

RTA Pacific Operations has written back bauxite ore from Ore Reserves to
Mineral Resources due to a routine review of price assumptions over the life
of the mine.

RTA Pacific Operations Ore Reserve estimate, for the Amrun deposit, has
decreased by 218 Mt, from 1,044 Mt to 826 Mt.  The reduction in Ore Reserve
estimate is associated with a routine review of price assumptions over the
life of the mine, and updated orebody knowledge.  There has been no material
change to the economic cut-off methodology or process.  There has been no
material change to the other reserve modifying factors, including
governmental, tenure, environmental, cultural heritage, social, community or
operational.

RTA Pacific Operations Mineral Resources exclusive of Ore Reserves, for the
Amrun deposit, has increased by 172 Mt, from 678 Mt to 850 Mt. The increase
was mainly due to changes in the forecast pricing assumptions used in the
reserving process. Those blocks removed from the 2021 Ore Reserve that are
physically located above the remaining economic blocks have also been removed
from the Mineral Resource.

RTA Pacific Operations Mineral Resources exclusive of Ore Reserves, for the
East Weipa and Andoom deposits, has increased by 28Mt, from 35Mt to 63Mt. The
increase was mainly due to changes in the forecast pricing assumptions used in
the reserving process. Those blocks removed from the 2021 Ore Reserve that are
physically located above the remaining economic blocks have also been removed
from the Mineral Resource.

Supporting information for the update to the Weipa Ore Reserve and Mineral
Resource estimates is set out in the release to the ASX dated 23 February 2022
"Changes to Rio Tinto Aluminium (RTA) Pacific Operations Ore Reserve and
Mineral Resource Estimates for Weipa".

Jadar Ore Reserves and Mineral Resources

As a result of the Government of Serbia in January 2022 cancelling the Spatial
Plan and revoking all related permits, Rio Tinto has decided to no longer
report an Ore Reserve for the Jadar lithium-borates project in western
Serbia.  Accordingly, the Mineral Resources estimate has been updated to
incorporate previously declared Ore Reserves, as well as additional drilling
data. This data was collected up to the end of 2021 and prior to the
Government cancelling the Spatial Plan, and has resulted in an updated
geological model, and reclassification of significant tonnage from Inferred to
Indicated Mineral Resource category. This change has been made to reflect the
current status of the project.

Rio Tinto remains committed to exploring all options and is reviewing the
legal basis of the decision by Government of Serbia and future implications
for our activities and our people in Serbia.

The Mineral Resources comprise 85.4 Mt of Indicated Resources at 1.76% Li(2)O
and 16.1% B(2)O(3) with an additional 58.1 Mt of Inferred Resources at 1.87%
Li(2)O and 12.0% B(2)O(3).

Rio Tinto committed $2.4 billion of funding to the Jadar lithium-borates
project, in July 2021, subject to receiving all relevant approvals, permits
and licenses and ongoing engagement with local communities, the Government of
Serbia and civil society.

The proposed project consisted of an underground mine, sustainable industrial
processing and waste facilities as well as associated infrastructure.
Production estimates included approximately 58 kt of battery grade lithium
carbonate, as well as 160 kt of boric acid (B(2)O(3) units) and 255 kt of
sodium sulfate as by-products per year.

Supporting information for the update to the Jadar Ore Reserve and Mineral
Resource estimates is set out in the release to the ASX dated 23 February 2022
"Rio Tinto updates Ore Reserves and Mineral Resources at Jadar".

 

Important notices

 

Winu Mineral Resources

The Winu Mineral Resource estimates referred to in this release were set out
in the release to the ASX dated 23 February 2022 "Rio Tinto reports first
Indicated Mineral Resource and 40% increase in contained copper at Winu
project" (Winu release).  The Competent Person responsible for the
information in the Winu release that relates to Mineral Resources is Mr James
Pocoe, who is a Member of the Australasian Institute of Mining and Metallurgy
(MAusIMM).

Copper equivalents have been calculated using the formula CuEq = ((Cu%*Cu
price 1% per tonne *Cu_recovery) + (Au ppm*Au price per g/t*Au_recovery) + (Ag
ppm*Ag price per g/t*Ag_recovery)) / (Cu price 1 % per tonne). Metal prices
applied were provided by Rio Tinto Economics and generated based on industry
capacity analysis, global commodity consumption and economic growth trends.
Details of recoveries are shown on an average basis for material types in the
Winu release.  It is the company's opinion that all the elements included in
the metal equivalent calculation have a reasonable potential to be recovered
and sold.

RTA Ore Reserve and Mineral Resources

The Ore Reserve and Mineral Resource estimates for RTA Pacific Operations
referred to in this release were set out in the release to the ASX dated 23
February 2022 "Changes to Rio Tinto Aluminium (RTA) Pacific Operations Ore
Reserve and Mineral Resource Estimates for Weipa" (RTA release).  The
Competent Person responsible for the information in the RTA release that
relates to Ore Reserves is Mr William Saba who is a Member of the Australasian
Institute of Mining and Metallurgy (MAusIMM). The Competent Person responsible
for the information in the RTA release that relates to Mineral Resources is Mr
Angus C. McIntyre, who is a Member of the Australasian Institute of Mining and
Metallurgy (MAusIMM).

Jadar Ore Reserves Mineral Resources

The Mineral Resource estimates for Jadar referred to in this release were set
out in the release to the ASX dated 23 February 2022 "Rio Tinto updates Ore
Reserves and Mineral Resources at Jadar" (Jadar release).  The Competent
Person responsible for the information in the Jadar release that relates to
Ore Reserves is Mr Allan Earl who is a Fellow of the Australasian Institute of
Mining and Metallurgy (MAusIMM). Mr Earl's assessment is supported from a
metallurgical perspective by Mr Gary Davis who is a Member of the Australasian
Institute of Mining and Metallurgy (MAusIMM) The Competent Persons responsible
for the information in the Jadar release that relates to Mineral Resources are
Mr Mark Sweeney who is a Member of the Australasian Institute of Mining and
Metallurgy (MAusIMM) and Mr Jorge Garcia, who is Member of the European
Federation of Geologists (EFG).

No new information

Rio Tinto confirms that it is not aware of any new information or data that
materially affects the information included in the Winu release, the RTA
release or the Jadar release (together, the ASX releases), that all material
assumptions and technical parameters underpinning the estimates in the ASX
releases and the production target in the Jadar release continue to apply and
have not materially changed, and that the form and context in which the
Competent Persons' findings are presented have not been materially modified.

 

 Contacts  Please direct all enquiries to media.enquiries@riotinto.com

 

 Media Relations, UK         Media Relations, Australia

 Illtud Harri                Jonathan Rose

 M +44 7920 503 600          M +61 447 028 913

 David Outhwaite             Matt Chambers

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 Media Relations, Americas   Jesse Riseborough

 Matthew Klar                M +61 436 653 412

 T +1 514 608 4429

                             Investor Relations, Australia

 Investor Relations, UK      Amar Jambaa

 Menno Sanderse              M +61 472 865 948

 M: +44 7825 195 178

 David Ovington

 M +44 7920 010 978

 Clare Peever

 M +44 7788 967 877

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This announcement is authorised for release to the market by Steve Allen, Rio
Tinto's Group Company Secretary.

 

riotinto.com

 

 

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