Welcome to our podcast! Today, we're diving into the Winu Project, a significant copper-gold-silver discovery by Rio Tinto in Western Australia's remote Pilbara region.
The Discovery and What Lies Beneath:
- Discovered in December 2017, Winu is interpreted as a structurally controlled, vein-hosted copper-gold-silver deposit within Neoproterozoic metasedimentary rocks. It is considered a new intrusion-related copper-gold deposit.
- The project is situated on the Anketell Shelf of the Yeneena Basin, which is entirely covered by Phanerozoic sediments, typically ranging from 50 to 100 meters thick.
- The mineralisation at Winu features primary sulphide deposits that are overlain by a supergene blanket containing secondary copper minerals and native copper. This supergene zone, where weathering has upgraded the mineralisation, can extend to average depths of 200 meters, and locally up to 340 meters.
- As of December 2021, the total mineral resource estimate for Winu is 503 million tonnes at an average grade of 0.45% copper equivalent (CuEq). This includes 57 million tonnes in the supergene zone and 446 million tonnes in the hypogene (primary) zone, both reported at a 0.2% CuEq cut-off.
How Exploration is Done:
- Exploration drilling at Winu utilizes a combination ofangled diamond (DD) and vertical and angled reverse circulation (RC) drilling methods. Core recovery from drilling is generally very high, typically exceeding 99%.
- Samples from both diamond core and RC drilling aremeticulously prepared and sent to an ALS Limited laboratory in Perth, where they undergo processes like drying, crushing, splitting, and pulverizing.
- Analysis includes 51 elements using 4-acid digestionfollowed by ICP-OES/MS measurements, and gold (Au) analysis by fire assay. Quality control measures, such as the inclusion of duplicates, blanks, and certified reference materials, are consistently applied to ensure acceptable accuracy and precision.
Moving Towards Mining Operations:
- The Winu Project proposes the development of an open-pit mine that will extend below the water table, employing conventional drill and blast, and load and haul operations.
- Key infrastructure for the mine will include waste rock landforms (WRLs) and a Tailings Storage Facility (TSF). The TSF will be constructed from waste rock, serving as a permanent storage location, and is planned to progressively build out to a final height of approximately 60 meters. Potentially acid-forming (PAF) waste rock will be encapsulated within non-acid forming (NAF) material during operations to manage environmental risks.
Environmental and Community Focus:
- Rio Tinto is actively addressing various environmental considerations for the project. The proposal indicates the clearing of up to 4,868 hectares of native vegetation within the larger 37,344-hectare Development Envelope.
- Extensive surveys have been conducted on terrestrial and subterranean fauna, identifying potential impacts on species such as the Northern Quoll (Endangered), Bilby (Vulnerable), and Fork-tailed Swift (Migratory). Measures to mitigate these impacts include specifying equipment design to be within Australian standard noise limits and shielding permanent lighting to minimize light spill in active mine areas.
- The Winu Project is located within the Native Title Determination Areas of the Nyangumarta and Martu people.
- Significant efforts in cultural heritage surveys, involving both Nyangumarta and Martu representatives, have been undertaken since 2017.
This project highlights the complex balance between resource development and environmental and social responsibility in remote Australian landscapes.
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Disclaimer:
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