The Roça Grande and Pilar deposits are located in the eastern part of the Iron Quadrangle, which had been the largest and most important mineral province in Brazil.

ROÇA GRANDE DEPOSIT
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). The North Structure (Structure 1) hosts the RG01 mineralized body and the South Structure (Structure 2) hosts the RG02, RG03, and RG06 mineralized bodies. The RG07 mineralized body is located immediately in the hanging wall of Structure 1 and is hosted mostly by a quartz vein. The bedding is well defined by the carbonate- facies iron formation and chert found in the BIF horizons, with an overall strike of azimuth 70º to 80º, and dipping approximately 30º to 35º south.

At the mine scale, folding of the iron formation stratigraphy is generally absent. Local folding and faulting in Structure 2 has been observed at the RG06 mineralized body where a 200 m to 300 m strike length of the stratigraphy has been folded.

PILAR DEPOSIT
The Pilar deposit is hosted by the basal units of the Nova Lima Group, and by sequences of the Quebra-Ossos Group. The rock packages in the immediate area of the mine are comprised of tholeiitic meta-basalts, mica-quartz schists, chlorite-quartz schists, quartzchlorite-sericite schists, and volcano-chemical and clastic meta-sedimentary rocks of the Santa Quitéria Unit (Nova Lima Group), and further to the east, of meta-komatiite flows (along with their intrusive equivalents) of the Quebra-Ossos Group.

Within the current footprint of the Pilar Mine, there are only two known zones of mineralization that outcrop at surface and which were previously mined in an open pit operation; South-West (SW) and São Jorge Synform. The currently mined BF and BF II zones are truly “blind” mineralized zones that occur at deeper levels of the Pilar deposit and were discovered and put into production by Jaguar only after the initial years of the underground operation.

The Pilar Mine occurs at the northernmost end of the northeasterly oriented Brumal-Pilar BIF trend. The Brumal BIF trend extends for many kilometres to the southwest from the Pilar deposit. In regional terms, the Brumal-Pilar BIF linear trend corresponds to a package of “Algoma-type” BIFs.

Regional mapping showed that the Brumal BIF trend within the Pilar mine site is folded into a considerably tight, overturned synform-antiform fold of approximately one kilometre in amplitude, with axes statistically plunging steeply to the southeast and with an axial-planar tectonic cleavage dipping steeply in the east-southeast direction.

The “Algoma-type” BIFs typically range between five metres and 15 m to 20 m in thickness, however, within the Pilar property, they have been severely and tightly folded and thickened as a result of a west-verging compressional regional deformation event that affected the entire eastern border of the Rio da Velhas Supergroup exposures in the Iron Quadrangle Terrain. Structural geometries recorded at the Pilar Mine indicate that the mine stratigraphic package may have been folded and re-folded during this event.

Stratigraphically, the Pilar BIF Unit is overlain by a two to five metre thick layer of carbonaceous phyllites, which in turn is overlain by a thick package of greenschists (meta- basic volcanic rocks - “Upper Basic Volcanic Unit”). The Pilar BIF Unit is underlain by a thick package of greenschists (“Lower Basic Volcanic Unit”).

Geological mapping and underground observations show that mineralized bodies of the Pilar BIF Unit represent scattered, generally stratabound lenses of “sulphide-facies” BIF ranging from 15-20 m to 100-200 m in strike-length and two metres to 10-15 m in thickness. In the Pilar deposit, the best grade BIF-hosted mineralized zones are typically located along the contact between the Pilar BIF Unit and the layer of carbonaceous phyllites that occurs immediately adjacent to the greenschists of the Upper Basic Volcanic Unit. The BIF-hosted mineralized bodies are conformably folded together with the whole Pilar BIF Unit at the deposit-scale “synclinorium” of the Pilar deposit (São Jorge Synform, BF II Antiform, Junction Synform, BF Antiform, BA Antiform).

MINERALIZATION
At Roça Grande, gold mineralization is more commonly associated with BIF horizons. In RG01, RG02, RG03, and RG06 mineralized bodies, the gold mineralization is developed roughly parallel to the primary bedding and is related to centimetre-scale bands of massive to disseminated pyrrhotite and arsenopyrite. In many cases, better gold values are located along the hangingwall contact of the iron formation sequence and is hosted by carbonate-facies iron formation. The grades generally decrease towards the footwall where the iron formation becomes more silica-rich. The thicknesses of the iron formations are observed to be affected by broad- scale boudinaged structures. Better gold grades are found in the thicker portions while the narrower portions of the boudinaged structures have lower grades. Late-stage, barren quartz veins are also ubiquitously present and also display a boudinaged form.

The economic gold mineralization at the Pilar Mine is hosted by the folded, and locally re- folded, Pilar BIF Unit including the SW, São Jorge, BF III, BF II, BF, LPA, and BA mineralized zones, and by the conformably folded Eastern Torre meta-volcanic sequence. The main zones of mineralization occur as scattered, stratabound lenses (or “pods”) of sulphide-facies BIFs within the “carbonatic-oxide-facies” deposit-scale Pilar BIF Unit. Economic mineralized bodies consist of stratabound, but not stratiform, concentrations of gold-bearing sulphides that occur in scattered grains, in seams, and in irregular-shaped granular aggregates located along and replacing iron carbonates-rich bands of the BIFs.

Individual quartz veins are typically less than one metre in width and can be observed to be of three generations. The quartz veins of the first generation are typically associated with the gold mineralization and are folded by the main tectonic event which affected the Pilar mine package as a whole. The quartz veins of the second generation are typically lower grade or barren and are not affected by folding. Lastly, the quartz veining of the third generation is associated to the above-mentioned extensional tectonic cleavage and may also be related to halos of mineralization/sulphidation where related to hinge structural domains.

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 Caeté Gold Mine Complex has two underground mines: Pilar Gold Mine (“Pilar”) and Roça Grande Gold Mine (“RG”). On March 22, 2018, the Roça Grande mine was placed on care and maintenance.

At Pilar, gold mineralization is contained within a shear zone with an average 50º to 60º dip. The mineralization is structurally complex due to intense folding and displacements (up to 2 m) due to local faulting. This results in direction changes and pinching and swelling of the ore zones over relatively short distances. The ore zones hangingwall (HW) and footwall (FW) contacts with the non- economic wall-rocks are almost everywhere visible by eye, though sampling shows that there are, on some occasions, a few surprising assay results (variable gold grades) within the ore-hosted BIF formation. The orebody is approximately 250 to 350 m along strike, and the orebody is accessed and mined along strike via crosscuts perpendicular to the orebody.

Mining Methods
Two mining methods are utilized at the Pilar operation: Cut and fill, that represents about 10% of the mining fronts, and Sublevel, that represents about 90% of the mining fronts. The Cut and Fill method is utilized for individual orebodies with irregular geometry and/or for individual orebodies that dip less than 45º; while the Sublevel method is utilized for thicker orebodies that dip more than 45º. The current LOM forecasts the Sublevel method as the largely predominant one at the Pilar operation in the future years.

The mine is accessed from a 5 m x 5 m primary decline located in the footwall of the deposit. The portal is located at the elevation 760 MASL. The mine is subdivided into levels, with Level 1 established at the elevation 690 m. Starting at this point, the vertical clearance is 75 m, i.e., Level 2 is at the elevation 615 m, Level 3 at the elevation 540 m, etc. A 3 m-thick sill pillar is left between levels. Sublevels have also been excavated from the main ramp at 15 m vertical intervals, aimed at providing an intermediate access to the mining panels.

At each level and sublevel, drifts are developed near the centre of the mineralized zone to expose the Footwall and the Hanging-wall contacts. The drift is extended in both directions along the strike, under geological control for alignment, continuing to expose the contacts, until the limits of the deposit are reached. This provides for two working faces per sublevel.

Longhole Mining is carried out on a longitudinal retreat sequence, towards the central access. Stopes are nominally 50 m in length and separated by partial rib pillars, depending on geotechnical modelling and ore geometry. When the mining of each longhole stope has been completed, the excavation is filled with the use of development waste. The sequence continues until the entire sublevel is mined. Mining then proceeds upward to the next sublevel and the sequence is repeated until the sill pillar is reached. Stopes are mined from several individual levels simultaneously, in order to provide the required number of active workplaces needed to meet production targets.

For Cut and Fill mining, the level development is carried out to the extent of the ore, then rockfilled. The subsequent cut is advanced using the breasting technique. Mining progresses in two directions from the access towards the ends of the orebody. Drilling of the breasts is completed using two-boom electric-hydraulic jumbos equipped with extension steel. This configuration allows for the normal 3.5 m long rounds to be extended to 7 m. Mucking is performed using six cubic yard Load-Haul-Dump (LHD) units and haulage to surface is by a fleet of 30-ton articulated haul trucks. Initial access to each mining panel is from the main level (at the base of the panel). As mining progresses, a 20% slope ramp is constructed in the fill to provide access to the next cut above the previously placed rockfill. As this internal ramp is constructed, the roof immediately above is raised, maintaining a clearance of 4.2 m. The excavation and rockfill sequence are repeated until the next sublevel (15 m above) is reached. The sequence is then repeated for a total of five sublevels until the next level is reached.

The mine is highly mechanized. Development and mining activities are accomplished with a fleet of two two-boom electric-hydraulic jumbos. Longhole drilling is completed with three Sandvik Fandrill drills. Four 6 cubic yard LHD Sandvik and one 3,8 cubic yard LHD Epiroc units are used for mucking. A fleet of five Volvo A30 trucks and one Iveco 23-tonne trucks are used to haul broken rock to surface.

Ground conditions were observed by RPA to be good. The main decline, portions of which were developed up to ten years ago, did not exhibit any roof or wall deterioration. Primary support in the mine is provided by the use of swellex, grouted rebar and, in the wider areas, grouted cable bolts. Two single-boom electric-hydraulic jumbos are used for rock bolting.

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%).

The Caeté processing plant has a design capacity of 720,000 tpa of ROM ore. The process flowsheet consists primarily of the following unit operations:
- Crushing
- Grinding
- Gravity Gold Recovery
- Flotation
- Leaching and CIP
- Gold Recovery
- Detoxification
- Tailings Disposal.

GRAVITY GOLD RECOVERY
Gravity concentration uses a Knelson centrifugal gravity concentrator to recover fine particles of free gold. The gravity concentrate proceeds to an Acacia intensive cyanidation reactor (Acacia), from which the gold bearing solution is pumped directly to a dedicated set of electrolytic cells. The precipitate from the cells is processed into doré bars in the refinery.

FLOTATION
The flotation circuit consists of a series of twelve 14.1 m3 (500 ft3) flotation cells, the first three operating as roughers, three operating as primary scavengers, three operating as secondary scavengers, and the last three operating as tert ........