The Carajás East hub includes the Antas Open Pit (completed in June 2021) and the Pedra Branca underground mine.

Pedra Branca
The area to the south of the deposit is dominated by a sequence of meta-gabbro-diorite interspersed with foliated pegmatites of granitic composition while the northern area is covered by a sequence of gneisses of granitic composition. The contact between the two rock units is represented by a shear zone which generally controls the distribution of the mineralisation with the Pedra Branca deposit comprising two zones of mineralisation, namely the “West” and the “East”.

The copper mineralisation is strong and pervasive, with various types of mineralisation (semi massive to
disseminated) being distinguished in the drill core.

Pedra Branca East (PBE) is an Iron Oxide Copper Gold (IOCG) type deposit located within the Carajás Basement, and is hosted predominantly by diorite and sheared granite. Country rocks are mostly biotitegneisses (ortho-gneisses), while pegmatite dykes are abundant in proximity to the ore zones.

This deposit occurs along an E-W striking regional shear zone, which is represented by metres wide mylonitic zones marked by intense silicification. This shear zone is regionally crosscut by north-south, northeast and northwest striking faults.

PBE consists of a single continuous orebody, which strikes east-west and has a >600m strike extension. It is a sub-vertical to steeply dipping (south) plunging shoot, with a thicker higher grade central core which follows the plunge. The orebody begins to shallow out in dip at depth, >400m below surface and beyond.

The ore zone itself is typified by zones of high grade breccia matrix ore (fragments of hydrothermal breccia cemented together by semi massive sulphides), which are interspersed with zones of lower grade disseminated mineralisation. The most dominant of the high grade zones is the Hanging Wall High Grade Zone (HW-HGZ), which sits on the hanging wall contact and is present across the entire depth and breadth of the PBE orebody. The hanging wall high grade zone has a sharp and easily identifiable “knife edge” contact.

Two main ore types are identified:

• Semi-massive, high grade breccia matrix ore: consists of hydrothermal breccia zones with matrix filled by magnetite and chalcopyrite, plus subordinate pyrrhotite and less pyrite. The clasts are made of altered host rock and coarse amphibole. The typical range of assays for this ore type is between 4.0% copper to 10.0% copper.

• Disseminated ore: a low to medium grade ore which envelops the high-grade zone. It consists of the same sulphide assemblage, which is also associated with magnetite that occurs as fine disseminations in the host rock, sometimes following the foliation, and also filling veinlets and fractures. The typical assays range from below cut-off grade (0.9% copper) to 2.5% copper.

Antas
The Antas North iron oxide copper gold deposit is hosted within the Carajás Mineral Province which is located in the southern part of the Amazon Craton. Locally the craton is overlain by metavolcanic–sedimentary units of the Rio Novo Group and the 2.76 Ga Itacaiúnas Supergroup. The Itacaiúnas Supergroup hosts all the known Carajás iron oxide copper gold deposits and is thought to have been deposited in a marine rift environment. The Carajás Mineral Province represents one of the best endowed mineral districts in the world and contains the world’s largest known concentration of iron oxide copper gold deposits including the, Salobo, Igarapé Bahia, Alemão, Cristalino, Gameleira, Furnas, Alvo 118, Antas, Pedra Branca and Pantera deposits.

The Antas North deposit is a structurally controlled iron oxide copper gold deposit which is spatially related to (WNW-ESE) regional shear zones, specifically the Carajás fault and the Cinzento shear system. Mineralisation is hosted within hydrothermal brecciated and altered felsic and mafic volcanic units. Mineralised fluids have been sourced from nearby large granitoid bodies and have been focussed along structural conduits resulting in the deposition of high grade (greater than 10 per cent copper) massive sulfide zones immediately adjacent to or within the interpreted main structural zone. These high-grade massive sulfide zones are commonly 2 to 5 metres wide and are surrounded by a broader zone of lower grade disseminated mineralisation grading 0.2 to 2.0 per cent copper.

The main zone of mineralisation at the Antas North mine has been defined over 350 metres along strike, 300 metres down dip and can be up to 35 metres wide. Mineralisation contains variable proportions of chalcopyrite, pyrrhotite, and magnetite. Mineralisation in the eastern part of the pit is offset and truncated by late stage dykes which, during emplacement, have remobilised mineralisation locally along dyke margins.

The main zone of mineralisation at the Antas North mine has been defined over 350 metres along strike, 300 metres down dip and can be up to 35 metres wide. Extensions of mineralisation along strike and down plunge to the west are considered possible. Economic mineralisation has also been identified near surface at the Azevedo deposit which is located 300 metres from the current Antas North pit limits. Azevedo mineralisation has currently been identified over a 140 metres strike length and a plunging down dip extent of 100 metres to 140 metres. The mineralisation at Azevedo is typically lower grade (~0.8% copper) and thinner (up to 10 metres wide) than mineralisation inside the Antas North pit.

The Company achieved a significant milestone with the start of mining ore from stopes at Pedra Branca, the first of the satellite mines to be realised under the Hub Strategy. In 2021 Pedra Branca’s successful transition from a concept study to being permitted, built and into successful commissioning and production within three years is proof of the Brazil team’s ability to deliver our Strategy.

The box cut, portal and initial few metres of decline was completed in 2016 and much of the infrastructure to resume its initial excavation is in place.

Sublevel stoping was selected as the mining method and has been deemed suitable for the orebody, based on orebody geometry and rock mass qualities.

Detailed infrastructure design was completed upon the mine design to address the required mine ventilation, mine dewatering, power supply, controls, and communication requirements.

The mine plan targets a ~1 Mtpa10 production rate, achieved in Q1 2022 with a total mine life of 8 years. Sublevel stoping with rock backfill will be applied in a bottom up bench stoping configuration. Stopes will be mined via long hole open stoping.

The pre-concentration and development waste will be utilised as backfill.

Mining of the Antas North open pit was completed in June 2021. The Company will continue to reclaim and process the remaining surface stockpiles into 2022 as the ramp-up and transition to full Pedra Branca feed occurs. The re-purposing of the Antas North open pit void as a tailings storage facility to support the future Carajás East hub operations has commenced. It will be available for use in 2022.

During 2021 year, Antas’ existing processing facilities located in the municipality of Curionópolis in the state of Pará were used to process ore mined at Pedra Branca, as well as ore from the Antas North mine.

Mining of the Antas North open pit was completed in June 2021. Oz Mineral will continue to reclaim and process the remaining surface stockpiles into 2022 as the ramp-up and transition to full Pedra Branca feed occurs.

Processing method: Ore sorting, conventional crushing, grinding, flotation and filtration.

Metal recovery estimates are based on actual performance: Copper and Gold recoveries are estimated by equations with the life of mine averaging 97% for Copper and the 84% for Gold, respectively.

Treatment and refining charges for the concentrate reflect average industry commercial terms and conditions, according to the concentrate quality.

The pre-concentrate process raises the average ROM ore grade from ~2.0% Cu, ~0 ........