The mineral resources comprise secondary oxide copper mineralisation that form as sub-horizontal blankets in the ferruginous saprolite horizon, immediately above underlying copper sulphide mineralisation which is structurally controlled. Oxide copper mineralisation occurs predominantly in the form of malachite, with minor amounts of azurite, chrysocolla, cuprite, and rare native copper. The primary sulphide mineralisation occurs as chalcopyrite and pyrite, with cuprite and chalcocite occurring in the transitional zone between the oxide and sulphide zones.

The Anthill deposit is hosted predominantly within the Esperanza Formation. The host lithology of the orebody is inferred to be dolomitic siltstones; however, the strong weathering and oxidation process has resulted in the near complete loss of dolomite from the rock in the upper oxide zone. The mineralisation appears to be controlled by a combination of steep structural elements and broad dome features. The Anthill transition is commonly hosted in structurally controlled silicified zones as well as in silicified sedimentary breccia in dolomite, which appear to have been a preferred permeability horizon for mineralising fluids.

Dimensions
Approximately 1,700 m x 770 m and ranges in thickness from less than 10 m to approximately 40 m; mineralisation is subdivided into three areas: Anthill East, Anthill West, and Anthill Link (low- grade).

The mining method is typical of other operations in the region and there are well established mining contractors who can provide the required mining services, comprising of rigid mining dump trucks, hydraulic excavators and rockdrills. Ore from the ROM area will be rehandled with front-end loaders into the road trains and hauled to the Mount Kelly ROM, where ore will be crushed, agglomerated, and radially stacked onto the leach pads. A conventional excavator and truck fleet scenario was compared with using Kenworth “bigfoot” trucks before progressing the study in the May 2020 Mining report completed by CSA Global. It was decided to go with conventional truck and excavator as road trains are more suited to wider and shallower pits.

Mining will involve blasting on 10 m benches with load and haul activities on three or four flitches of varying heights. It is planned to use three flitches in large waste zones in the upper parts of the pit with a larger excavator, and four flitches in the ore with a smaller excavator. This approach can ensure selective mining while utilising blast-hole sampling for grade control, as there is a requirement to mine ore and waste with a minimum of dilution and mining ore loss.

The pit shells and lobes of mineralisation were then subdivided into the stages:
• Stage 1 East: The Starter Pit to the east, enabling to reach some ore and defer waste rock stripping;
• Stage 1 West: Excavation focused on the small West Pit;
• Stage 2 East: Expansion of the Starter Pit to the east to final pit cutback design;
• Stage 2 West: Development of Starter Pit to the west to final cutback design.

Pit designs have also included parameters related to the pit ramp dimensions:
• Dual-lane haul roads to be 25 m wide;
• Single-lane haul roads of 15 m, reducing to 12 m within 10 m of pit base;
• Haul road gradients of 1:9 (11%) increasing to 1:8 (12.5%);
• Incorporating previously designed Johnson Creek diversion structures.

The current Austral mine schedule has the Stage 1 East pit being backfilled up to 355 mRL, which is approximately 15 m above the original void, and has no waste rock going into the Stage 1 West Pit.

The Mt Kelly heap leach processing facility is well established and the ore from the Anthill project will extend the life of the operation. The product is copper cathode sheets that will be selling into an existing offtake arrangement.

Stockpiled ore at Mt Kelly is loaded into the crushing circuit where the ore is sized, agglomerated (pre-treated with acid and spent leachate (raffinate) solution to start the leaching process) and then conveyed to a radial stacker for placement on the leach pads. Throughput at full production is planned to be 5,000 tonnes per day. Ore is stacked on prepared leach pads to a height of 4 to 8m. The leach pads are irrigated with dilute sulphuric acid to percolate through the stacked ore and dissolve the oxide copper into pregnant leach solution (PLS). This PLS is gravity fed to lined ponds for further processing. The leach process yields >60% copper recovery after 3 months of leaching, 80% recovery after 6 months, and a planned overall 85% copper recovery after 12 months of leaching.

The purpose of Solvent Extraction (SX) is to receive the pregnant leach solution (PLS) from the heap leach pads and purify and concentrate it into a synthetic, relatively pure solution from which t ........