The Surubim District, containing the Surubim OP Mine (including planned production from underground), located at 9°34’12” S and 39°51’52” W, also includes the C-12 OP/UG Mine, located at 9°34’44” S and 39°52’27” W, the Lagoa da Mina project, located at 9°30’13” S and 39°47’48” W adjacent to the past producing Angicos Mine, the Cercado Velho project, located at 9°30’36” S and 39°47’52” W and the Terra do Sal project, located at 9°38’1” S and 39°49’6” W.

The Surubim District is located in the central part of the Curaçá Valley. The C12 deposit is located 1.2 km to the SW of the Surubim Mine. The Cercado Velho and Lagoa da Mina deposits are approximately 10 km to the NE of the Surubim Mine whereas the Terra do Sal deposit is situated 8 km to the SE of Surubim Mine. The Surubim Mine and C12 Deposits are hosted in the Surubim gneiss (alternating tonalitic and granorioditic bands with gabbro and diorite bands) whereas the other three deposits of the Surubim District are hosted in the Caraíba gneissic complex (biotite orthogneiss with local migmatite). The geology of the Surubim Mine and C12 deposit consists of large gabbro-dominant units with minor pyroxenite units and remnants of gneiss that are at least 400m wide. In both deposits, the mafic-ultramafic units are intruded by late north-striking granite and pegmatite dykes. The geology of the Cercado Velho, Lagoa da Mina and Terra do Sal consist of orthogneiss and migmatites intruded by ultramafic units measuring a few ce ........

There are six open pit projects in Curaçá Valley, the N8/N9 OP Mines and the N5 OP Mine, within the Vermelhos District; the Suçuarana OP Mine, in Pilar District; and the Surubim and C12 OP Mines in the Surubim District. In total, approximately 26% of the total copper metal produced in the LOM plan is expected to come from open pit operations within the Curaçá Valley.

The open pit operations of Curaçá Valley utilize conventional open pit mining, implementing proven drilling, blasting and loading / haulage equipment and technologies used in prior open pit operations within the Curaçá Valley by the Company.

To prepare ore for mining, the waste material located in the upper portion of the deposits (mostly comprised of waste rock and oxidized mineralization) is stripped mechanically by a bulldozer. While variable, the weathered profile is, on average, 15m to 20m in thickness throughout the Curaçá Valley. Waste material generated during stripping is stacked outside of the pit area, following the technical and environmental recommendations for each open pit mine.

After pre-stripping, hard rock mining of both barren waste and ore comprising the mineral reserves will be carried out by blasting with explosives. Primary rock drilling will be performed using hydraulic drills rigs with 127mm diameter blast holes, and a 2.40m x 4.80m staged mesh. The explosives, blasting agents and blasting accessories are supplied by a licensed explosive supplier, readily ........

Ore is transported from the Vermelhos UG Mine and the Surubim Mine to the Caraíba Mill complex via the Curaça Valley Haul Road, which passes adjacent to the Surubim Mine in the central portion of the Curaçá Valley, over a total transport distance of approximately 80 kilometers.

Caraíba Mill
The stockpile feeds two primary double deck screens, configured with 100mm aperture on the top and 40mm aperture on the bottom decks. The material over 40mm feeds one of two secondary cone crushers (seven-feet (“ft.”) standard Symons; 1,400t/h of capacity each) set to 28mm aperture. Screen undersize and secondary crushers products discharge onto one conveyor in an open circuit configuration.

Secondary cone crusher discharge and primary screen fines are blended with tertiary crusher discharge and are conveyed to the seven secondary double screen decks, configured with 25mm aperture on the top and 16mm aperture on the bottom decks. Tertiary crushing is performed with four standard CH660 Sandvik cone crushers (capacity of 350t/h each) set to 20mm aperture. Oversize material passes to the tertiary crushers operating in a closed-circuit configuration. Final product from the combined crushing and screening operations is 88% passing 1/2”.

Crushed ore is conveyed to the stacker-reclaimer system to further homogenize the ore for feeding the plant. The stacker-reclaimer system is comprised of a two-armed stacker and a 16 bucket-wheel reclaimer with capacities of 1,600t/h and 1,200t/h, respectively. Crushed ore capacity of the stacker-reclaim system is currently 140,000 tonnes.

GRINDING
The grinding circuit consists of two identical lines operating with a primary ball mill operating in closed circuit with a dedicated battery of 26” hydro-cyclones. Each ball mill is 5.0 m by 7.6 m, charged with 90 mm in diameter high chrome cast steel balls. The nominal grinding capacity of each mill is 200 t/h each. Typical ball consumption is 340 g/t.

Blended ore from the stacker reclaimer is withdrawn through belt feeders below one of the 3,000 tonne ore silos that are interconnected. Ore is delivered to the ball mill over a belt weightometer to control and measure the mass of ore sent to each mill for metallurgical accounting purposes.

The coarse fraction from the cyclone underflow recycles to the ball mill feed chute for further grinding. Overflow from both grinding lines combines as feed to the high frequency screeners and regrinding circuit.

HIGH FREQUENCY SCREENS AND REGRINDING CIRCUIT
The cyclone oversize is pumped to high frequency screening operations comprised of eight screens with five decks each of 105+ micron aperture. The high frequency screening coarse fraction is gravity fed to the vertical mill (STM HIG Mill HIG2300/23000) for regrinding, operating in an open circuit. The HIG Mill (High Intensity Grinding mill) was commission in September 2020. The screening operation fines combine with the regrind mill product and are pumped to the flotation.

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