Hillside copper-gold project is located in South Australia. (Credit: Rex Minerals Ltd)
The project is being developed by Rex Minerals. (Credit: Rex Minerals Ltd)
The Final Investment Decision (FID) for Hillside project is expected by mid-2023. (Credit: Rex Minerals Ltd)

Hillside project is an advanced stage, fully permitted copper-gold project in Australia. The project, fully owned by Rex Minerals, is located in the state of South Australia, approximately 165km from Adelaide.

Discovered in 2008, the Hillside project was granted the Mining Mineral Lease (ML), Extractive Minerals Lease (EML), and Miscellaneous Purposes Licence (MPL) in September 2014.

The South Australia Government approved the Program for Environment Protection and Rehabilitation (PEPR) for the copper-gold project in July 2020.

Rex Minerals completed an Extended Feasibility Study for the Hillside project in 2015.

In December 2022, the company announced its plans to advance with project financing and operational readiness plans after the completion of an Optimised Feasibility and Definition Phase Engineering Study (OFS).

The OFS estimated a pre-production capital cost of A$854m ($598m) for the project, including full fleet, pre-strip and contingency.

The pre-development activities commenced in 2022 and Rex aims to take the Final Investment Decision (FID) for Hillside copper-gold project by mid-2023.

Hillside is expected to deliver the first concentrate by the fourth quarter of 2025, subject to financing.

Hillside project location details

Hillside project is situated around 12km south of the Ardrossan township on the Yorke Peninsula of South Australia.

A portion of the Yorke Highway will be realigned, and surrounding roads will be modified and upgraded to improve access to the mine. This will facilitate the delivery of final product via trucks to Port Adelaide.

The project will receive electricity from via South Australian power grid. It will use sea water for processing and mining operations.

Geology and Mineralisation

Hillside is an Iron-Oxide-Copper-Gold (IOCG) orebody, located close to the historic mines of Moonta and Wallaroo.

The mineral resource is found within the Moonta Subdomain of the Olympic copper-gold (Cu-Au) Province of the eastern Gawler Craton of South Australia.

Copper-gold mineralisation occurs in a sequence of steeply west-dipping, intensely altered structures. The mineralisation has been observed across an area of 2.3km north-south length and a 900m west-east width.

Primary copper zones have parallel, steeply-dipping structures of massive sulphide dominated by chalcopyrite with subordinate bornite and chalcocite, while gold is found as inclusions within chalcopyrite.

The sulphides also contain uranium and magnetite.

Hillside Project Reserves

As of December 2022, the Mineral Resource Estimate (MRE) for the Hillside Project is estimated to be 337Mt (million tonnes) @ 0.56% Cu and 0.14g/t Au, containing 1,897 kilo tonnes (kt) of copper and 1,528 kilo ounces (koz) of gold.

The ore reserves stand at 186Mt @ 0.53% copper and 0.14g/t gold, containing 989kt of copper and 834koz of gold.

Mining and Ore Processing

The Hillside project will involve development of an open pit mine with an associated process plant and ancillary infrastructure.

A conventional open pit extraction process will be employed for mining. It will involve drilling and blasting for rock breakage and wall control, while hydraulic excavators and trucks will be used for primary haulage.

Rex will use a conventional flotation processing method for the separation of copper from the ore. The process tailings will be delivered to a dedicated Tailings Storage Facility and the concentrate to be transported in trucks via road for subsequent shipment from Port Adelaide.

The Stage I open pit operation will involve five phases with selective ore mining and stockpiling.

The Stage I Mine Plan may transition into Stage 2 by Year 5, subject to further board and regulatory approvals.

The annual production from the Stage 1 Mine Plan will be 151,500 tonnes of copper concentrate containing 42,000 tonnes of copper and 30,500oz of gold.

The 11-year mining plan will exploit 51% of this ore reserve and 26% of the mineral resource.

The processing plant throughput will be 6Mtpa initially but may increase to 8Mtpa after achieving stable operations.

Contractors Involved

The Hillside Ore Reserves by Rex were determined from a mine design developed by AMC Consultants and mineral processing work by Ausenco.

Consulting firm Resonate was engaged to undertake noise modelling, a comparison of predicted noise levels for each stage of operation and agreed noise criteria, and to determine conceptual noise mitigation measures in an Operational Noise Assessment report. The company also assisted in the development of the environmental protection and rehabilitation (PEPR) programme.

In March 2022, Rex contracted Ausenco for Engineering, Procurement, and Construction Management (EPCM) services for the Hillside Copper Project.

CIMIC Group company Thiess was selected as the preferred tenderer for mining services.

In February 2023, Rex Minerals commenced a process to evaluate partnering options for Hillside. The company hired Macquarie Capital (Australia) to assist in managing the partnering process.