The Pilar and Roça Grande deposits are examples of the Algoma BIF-hosted type. The main geological characteristics of this group are summarized as follows:

- Main host/fertile “Algoma-type” BIF Units: These units host the mineralization and are stratigraphically located at the waning stages of major volcanic cycles of the Rio da Velhas greenstone belt.

- Mineralization style: The mineralization consists of mainly “lateral” replacements/sulphidations of the iron carbonate-rich bands of the host Algoma-type BIF units. However, the BIF-hosted gold mineralization is not syngenetic in nature (in relation to the deposition of the host rock packages), rather it is clearly an epigenetic event that has occurred after the formation of the host rock units.

- Dimensions of the economic orebodies: Economic strike-lengths of only 50 m to 350 m for individual mined zones. Average thicknesses of the BIF-hosted orebodies may range from 2 m to 20 m.

The Roça Grande Mine is located in the upper unit of the Nova Lima Group. The dominant rock types found in the mine are a mixed assemblage of meta-volcanoclastics and meta-tuffs.

Two important BIF horizons are present at the Roça Grande Mine and they are separated by a central unit of sericitic phyllites and schists. The two BIF horizons are roughly parallel and are called Structures 1 and 2. In general, the southern BIF unit (Structure 2) is thicker than the northern BIF unit (Structure 1). ........

Roça Grande exclusively uses the mechanized horizontal cut and fill mining method.

The Roça Grande mining activity has historically focused on surface exposures of gold deposits, where the orebody outcropped. The outcrops were mined using open-pit mining techniques, with exploration focused solely on the immediate down-dip projection of gold mineralization, and minimal exploration along strike between the outcrops. Underground, the RG operations team continues to evaluate more effective methods to mine the 1–2 m wide veins without excessive dilution, using a frontal-attack mechanized cut-and-fill mining method.

On March 22, 2018, the Roça Grande mine was placed on care and maintenance.

CRUSHING
The ore from the Pilar and Roça Grande mines is transported by trucks to the crushing circuit and placed in the ROM stockpile. The crushing circuit is made up of a CJ411 - 111 kW primary jaw crusher in open circuit, and secondary (CH440-223 kW) and tertiary (CH440 223 kW) cone crushers operating in closed circuit.

The ROM stockpile ore is fed to the jaw crusher with a front end loader though a grizzly and vibrating feeder. The jaw crusher discharge feeds a multi deck screen (3,500 mm x 1,800 mm – with three panel decks consisting of apertures of 75 mm, 35 mm, and 16 mm respectively top to bottom), the undersize of each deck feeds secondary crushing, tertiary crushing, or the final product conveyor respectively. The secondary cone crusher operates in closed circuit with a double deck screen (5,700 mm x 2,400 mm – with two panel decks consisting of 35 mm and 16 mm apertures). Product from the double deck screen either recirculates back to the secondary crusher, feeds the tertiary crusher, or goes to the final product conveyor. The tertiary cone crusher operates in closed circuit with a single deck screen (3,500 mm x 1,800 mm – with a panel deck aperture of 16 mm), with the oversize recycling to the crusher and undersize product going to the final product conveyor, which discharges onto the crushed ore stockpile. The final particle top size of the crushing process is 16 mm.

GRINDING
The grinding circuit consists of a 2240 kW ball mill (5 m x 6 m EGL) with a capacity of up to 100 tonnes per hour, operating in closed circuit with a series of hydrocyclones. The overflow from the hydrocyclones (-200 mesh or -74 µm) proceeds to the flotation circuit, and the underflow (+200 mesh or +74 µm) either feeds the gravity concentration circuit (75%) or is recycled to the ball mill feed (25%).

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