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.

Antas is an on-going operation. The topography at the reporting date was matched to the Mineral Resource inventory for the conversion to Ore Reserve after pit optimization and detailed mine design. A mine plan was produced with the required detail to complete the definition of the Modifying Factors to Ore Reserve standards.

The orebody characterization was combined with the required production targets as of 0.8 Mta for the ore with total movements at a ratio of 2.5 Mta (for an average strip ratio as of 2.2) to define the Antas North open pit operation parameters. Hard rock mining equipment is a composition of 45 t and 100 t backhoes matched to 30 t trucks and assorted support equipment used to mine 10 m benches configurations with double and triple benches at the pit bottom. Production drilling is executed in 76 mm diameter holes in a typical 2.8 m x 3.2 m pattern, emulsion explosives and non-electrical detonating systems are applied for rock blasting.

The ore is categorized according to the copper grade in three ranges for short-term planning and blending: high, medium and low grade, ranging from 0.5% Cu to 1% Cu, 1% Cu to 3 % Cu and above 3% Cu, respectively. Blasted ore is transported to the short-term stockpiles at the ROM pad, adjacent to the primary crusher and blended to feed the plant.

The waste rock, below 0.5% Cu, is also stockpiled separately, according to whether it is mineralized or not. Ore sorting testwork is underway to be potentially applied to the mineralized waste to be fed to the plant at the end of the mine life.

The Mineral Resource information is detailed by reverse circulation drilling with drill spacings from 10 m to 5 m to produce the grade control model, used for short-term planning.

Geomechanical stability analyses and follow-up are performed in regular basis and their guidance has been relied upon for the pit optimization, design and scheduling for the Ore Reserve as well as operations. Particularly, the pit bottom has been implemented with steeper slope angles in double and triple benches configurations of 20 m and 30 m high benches, respectively. This results a significant reduction of the strip ratio and positively impacts the financial performance for the Antas North operation, on the other hand, geomechanical risks are increased and require close monitoring and control.

The pit optimization was run with average 63 degrees for the inter-ramp slopes for the fresh rock pit bottom – the overall slope for the 170 m deep pit is 58 degrees. After the selection of the optimum pit, detailed design was completed with 10 m high benches, finalized in double and triple benches configurations at the pit bottom and ramps grading maximum 14%, with 9 m final berms. The minimum operational width at the pit bottom is 15 m. The detailed pit design was used to define the life-of-mine schedule for the Ore Reserve and further financial analysis.

Operational dilution is projected as of 6%. Reconciliation analysis show that operational dilution is an issue of concern and must be closely followed-up for adjustments as necessary. For mixed blasts, with ore and waste, the ore type and waste are painted on the blasted material to identify the destination for the excavator operators and truck drivers.

Mine recovery is estimated as of 95%.

For determining the Ore Reserve estimate, Measured and Indicated Mineral Resources, only, were assigned economic value in the pit optimization, with Inferred Resources assigned zero NSR value, with their corresponding mining costs retained.

Additional Mineral Resources are planned to be mined in conjunction with the Ore Reserve, which represent a supplementary approximately 0.1 Mt @ 0.9 % Cu and 0.2 g/t Au, plus lowgrade material accounting for approximately 0.1 Mt @ 0.2 % Cu and 0.1 g/t Au. Future grade control drilling will target the former resources for upgrading to ore reserves. Ore sorting technology under trials may render the later economic, as well, in the future. The financial analysis of the Ore Reserve, only, exclusive of these materials, demonstrated positive economic results.

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

IOCG deposits such as Antas North are amenable for the production of copper and gold concentrates via conventional and well-established flotation routes in the existing plant.

The plant capacity at Antas North is 0.8 Mtpa, used as an assumption for the production plan. Metallurgical assumptions are based on comprehensive metallurgical test work that has been completed for the Antas North deposit and reconciliation results.

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.

The Antas North concentrate typically averages approximately 27% Cu and has low concentrations of deleterious elements (such as As, Bi, F, Hg and U); it is a desirable highquality saleable concentrate on the global market. OZ Miner ........