The Vermelhos District is located 60 km north of the Caraíba Mine. In this district, copper mineralization has been identified over 4.5 km in a NNE direction including the Siriema deposit (N5), the Vermelhos Mine (N7), the N8, N9, and N10 deposits. The Vermelhos Mine area is largely covered by quartz-rich colluvium with rare outcrops occurring along drainages. The deposits are located within the gneiss of Tanque Novo Complex, comprising orthogneiss (enderbitic and tonalites gneiss with local garnet gneiss units) which have undergone granulite facies metamorphism and were cross-cut by mafic to ultramafic intrusions. The well-foliated enderbitic gneiss is characterized by plagioclase, quartz, microcline, orthopyroxene, and biotite with minor magnetite. The garnet gneiss is formed by plagioclase, quartz, phlogopite, and garnet and gneissic fabric is marked mostly by phlogopite and stretched plagioclase crystals. This unit is not magnetic. The mafic rocks are composed of the norites, gabbros, and gabbro-norites. The ultramafic rocks are the main ore host of the copper mineralization and are composed by pyroxenites, and melanorites. The gneiss and mafic-ultramafic rocks are cross-cut by late, steep westerly-dipping, N-S to NNE-SSW trending, granite and pegmatite dykes measuring a few centimeters up to 40m thick. The pegmatite dykes extend from the Siriema deposit to the N8 deposit. Minor late quartz veins and diabase dykes cross-cut all lithologies. The gneissic country rocks ........

The Vermelhos UG Mine is located approximately 80 km north of the Pilar UG Mine and the Caraíba Mill, and it has been in operation since 2018. The main Vermelhos UG Mine deposit remains open along strike and at depth, and Ero Brasil is actively exploring extensions of the deposit to depth, and to the south of the main Vermelhos UG Mine in an area known as the Southern Vermelhos Corridor.

The Sublevel Open Stoping method (“SOS”) was chosen as the mining method at Vermelhos UG Mine considering the dip, plunge and thickness of the orebodies as well as the rock quality designation and overall competence of the host rock. Variations of this method are planned for the central area for maximum possible recovery using the CRF technique.

The mine design is based on current mining practice and entails mining panels of 15m to 35m, on average, in the vertical dimension without the need for rib pillars to support the open excavations. In the central and western high-grade areas (known as Toboggan and Sombrero) mining occurs using sub- horizontal stopes. In these areas, the panel size has been reduced to 25m and is filled using CRF to maximize mining recoveries and limit in-situ stresses.

Within the Vermelhos UG Mine, the vertical sections of the deposit typically range from 2.5m to 8.0m wide, with strike dimensions of up to 80.0m. Within the sub-horizontal high-grade portion of the deposit the dimensions are approximately 195m in length, 75m in thickness ........

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 blended product of the primary crushing operations is transported via conveyors to a feeder stockpile with a capacity of 12,000 tonnes. 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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