The Maracás Project is Vanadiferous Titano-Magnetite (VTM) deposit.

The NNE-striking, ~70° ESE-dipping Paleoproterozoic Rio Jacaré Intrusion occurs throughout the 40 km long Maracás Project exploration permits. Along the strike of the Rio Jacaré Intrusion within the property, several discrete deposits or areas containing vanadium-rich titanomagnetite bodies have been defined, namely the Gulçari A (Campbell) deposit, the Gulçari A North (GAN) deposit, Gulçari B deposit (currently part of GAN), the Sao Jose deposit (SJO), the Novo Amparo (NAO) deposit and the Novo Amparo North (NAN) deposit. Each of these deposits are located at various stratigraphic heights within the Rio Jacaré Intrusion, and thus occur within different cyclic units.

Within all deposits, mineralized bodies consist of magnetitite layers or magnetite pyroxenite layers formed as cyclic magmatic units associated with the surrounding gabbro. Typically, magnetiteenriched units have sharp magmatic contacts with units below and gradational contacts with the units above.

The Gulçari A deposit (also referred to Campbell Pit) is hosted in the lower parts of the Upper Zone of the Rio Jacaré Intrusion, between cyclic units C1 and C6, with magnetite mineralization hosted predominantly within the C3 unit. This C3 unit comprises medium to coarse-grained gabbro containing lenses of magnetitite, magnetite-pyroxenite and pyroxenite. These lenses are interpreted to pinch out along strike (i.e. in a N-S direction), and it is within this C3 unit that the largest concentrations of vanadium-rich magnetite known on the property are found (Brito, 1984). This magnetite deposit extends for approximately 350 m along strike, is up to 150 m wide and has been intersected in drilling to vertical depths of at least 300 m, and it likely extends below these depths. The deposit has been disrupted by northwest-southeast faulting (Figure 7.6).

The magnetite-pyroxenite body at the Campbell deposit was previously interpreted as a separate pipe-like intrusion cross-cutting the gabbro (Sá, 1992), but more recently has been understood as having formed within the feeder zone of the Rio Jacaré intrusion and representing one of the lower cyclic units (the C3 unit) of this intrusion.

Elements of interest at the Maracás Mine are vanadium and titanium. Vanadium is hosted within titaniferous magnetite, which is the major oxide phase found within the deposit. Ilmenite forms a second oxide phase which is commonly present, and which hosts titanium mineralization. Magnetite occurs as primary magmatic crystal grains that may be partly to martitized. These occur as anhedral grains, with grain sizes of between 0.3 mm and 2.0 mm, that form a polygonal mosaic together with ilmenite, which generally occurs as discrete anhedral magmatic crystals but may also occurs as inclusions within in the titaniferous magnetite, commonly displaying exsolution textures. Magnetite from the lower cyclic units (particularly the C3 unit at the Campbell deposit) has higher V2O5 concentrations than magnetite from the upper cyclic units – this is consistent across all deposits and is typical of layered magmatic magnetite deposits.

Massive magnetitite bodies are formed by ilmenite-magnetite heteradcumulates that form 2 cm to 3 m thick layers containing variable amounts of clinopyroxene. They occur together with layered mafic and ultramafic cumulates, which consist of olivine-magnetite cumulates and clinopyroxenemagnetite heteradcumulates, and together form rhythmically micro-layered gabbro, magnetite, and magnetite-pyroxenite bands.

In addition to primary magnetite, fine-grained magnetite also occurs locally as inclusions within silicate grains, and is the result of alteration of iron-rich silicates (e.g. uralitization of pyroxene and serpentinization of olivine).

Silicate phases associated with the magnetite include augite, plagioclase, hornblende, and rare grains of clinopyroxene, olivine and spinel. Rare olivine and pyroxene grains are observed within the magnetitite, but most are altered to serpentine or chlorite. The Rio Jacaré Intrusion has been intensely metamorphosed, so the pyroxene compositions observed probably reflect metamorphic re-equilibration rather than original magmatic compositions.

Sulphides (chalcopyrite and pentlandite with rare pyrite and pyrrhotite) are minor, and only account for up to 1% of the rock within the magnetitite units. Chalcopyrite is more abundant than the other sulphides and is most common in the rock types containing 50% magnetite or less. It commonly occurs in association with magnetite or ilmenite enclosed by amphibole and plagioclase. Pentlandite is much less abundant and occurs within in the magnetitite. Minor sphalerite and galena grains are found together in the silicates, associated with the other sulphides especially in the magnetite-poor rock types. However, the dominant trace minerals are nickel and cobalt sulphides and arsenides and cobalt-rich pentlandite. In many cases the arsenides are associated with the sulphides and appear to be alteration products of the sulphides.

In addition to the vanadium and titanium that form the focus of exploration and mining at the Maracás Mine, elevated platinum and palladium values have been found associated with magnetite-rich zones in the Rio Jacaré Intrusion. They are much richer in platinum-group metals than the surrounding silicate rocks, and there are significant correlations among all the PGMs and between PGM and copper.

In the magnetite zones, palladium-rich minerals, especially bismuthides and antimonides, are the most abundant PGM minerals. In most cases, these occur with interstitial silicates or within silicate inclusions in magnetite and ilmenite grains, and are associated with pentlandite and, in a few cases, with arsenides. Sperrylite is the most abundant platinum mineral and is associated with silicates interstitial to magnetite and ilmenite grains. At sites where the igneous mafic minerals have been altered to amphiboles, sperrylite may be altered to platinum-iron alloys.

Oxidation
In the Maracás area the water table generally lies 30 m below surface. The rocks are generally fresh below this water table and over it they weather and oxidize to varying degrees, with deeper oxidation in the proximity of faults, that may provide a conduit for fluid ingress. In weathered zones, silicate minerals generally weather (to clay minerals) more rapidly than oxides weather (Figure 7.14). Oxide minerals such as magnetite and ilmenite oxidize to other minerals such as maghemite, hematite, goethite and other iron oxides. The main effect of weathering/oxidation is a potential reduction in vanadium recovery to the magnetite concentrates – since the oxidized products of magnetite (e.g., hematite) are not magnetic, increased weathering may result in a lowering of vanadium recoveries.

The Maracás Vanadium Project is an open pit operation utilizing a contract mining fleet of hydraulic excavators, front-end loaders and 36 tonne haul trucks.

Currently, Largo has a mining fleet contract with Minax Tranportes, Construções e Mineração, which consists of 4 Volvo EC750 hydraulic excavators equipped with a 2.5 m3 bucket and a total of 24 Scania 8x4 36-tonne capacity trucks. The contract drilling fleet consists of 6 Sandvik Ranger DX800 rotary drill rigs.

The disposal of waste rock, and low grade mineralized material will be executed on an area close to the pit. The site shall be adequately prepared to include drainage at its base and channels to direct the flow of water with the aim of aiding geotechnical stability and mitigating the erosion of the stockpiled material.

The operation of this phase, in accordance with the ascending method, shall begin during the construction of the heap at the base of this area. Waste rock will be disposed by truck, which will then be uniformly distributed and leveled by an operator using a tractor. The procedure is then repeated, stacking another bank above the original one, while maintaining a ramp for the trucks to be able to access the area.

Pit Optimization Parameters for Campbell Pit:
- Angle between ramps: 37.5-64 Degrees;
- Face Angle: 55-80 Degrees;
- Berm width: 6 m;
- Bench height: 10-20 m.

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The Maracás vanadium recovery plant was commissioned in 2014 and achieved its nameplate capacity in 2018. In 2021, improvements in the roasting/burning system increased the production capacity to 13,200 t/year V2O5 At the time of writing this report, the plant produces up to 1,087 t of V2O5 equivalent per month with a trend approaching design capacity of 13,200 per year.
Maracás Vanadium plant is commissioning a new reactor that transforms AMV into V2O3 as final product. This project should be concluded at the end of 2021. At that time Largo will be able to produce 5,000 tonnes of V2O3/year (5,760 tonnes of V2O5 equivalent). This will not increase the total plant capacity, which will stay at 13,200 tons of V2O5 equivalent per year.

The current process flow sheet comprises three stages of crushing, one stage of grinding, two stages of magnetic separation, magnetic concentrate roasting, vanadium leaching, ammonium meta-vanadate (AMV) precipitation, AMV filtration, A ........