Source:
p. 7,15
The property consists of eighteen (18) concessions totalling 17,690.5 hectares, and all of the permits are owned 100% by Vanádio de Maracás S.A. (“Vanádio”), which is controlled 99.94% directly and indirectly by Largo. The remaining shares of Vanádio are owned by Companhia Baiana de Pesquisa Mineral, an entity controlled by the Brazilian State of Bahia.
Deposit Type
- Intrusion related
- Magmatic
Summary:
Work carried out to date indicates that the Maracás vanadium-rich titaniferous magnetite deposit is situated in a geologic environment similar to other magmatic vanadium-rich magnetite deposits. The Rio Jacaré intrusion that hosts the deposit is a mafic to ultramafic layered intrusion characterized by both rhythmic and cryptic layering that includes a pyroxenite/gabbro layer in the upper part. This gabbro layer hosts the Campbell vanadium deposit. The deposit has been assigned this way by the manner in which it was generated as an early magmatic ore type deposit formed by concentration through liquid immiscibility.
The vanadium at Maracás is associated with the titaniferous magnetite. Within the deposit, the titaniferous magnetite is the major oxide phase, followed by ilmenite. Magnetite occurs as primary grains that may be partly martitized. There is also fine-grained magnetite as inclusions in the silicate grains. This magnetite occurs as a secondary alteration after uralitization of pyroxene and serpentinization of olivine.
The magnetite normally occurs as anhedral grains, with grain sizes of between 0.3 and 2.0 mm, and forms a polygonal mosaic together with ilmenite. Ilmenite also occurs as inclusions in the magnetite, commonly displaying exsolution textures. Silicate phases associated with the magnetite include uralite, augite, plagioclase, hornblende, and rare grains of clinopyroxene, olivine and spinel. Magnetite from the magnetitite in the Lower zone (Campbell) has higher V2O5 concentrations (0.9% to 7.0%) than magnetite from the Upper zone (Gulçari B and Novo Amparo, 0.3% to 2.5% V2O5; Brito, 2000).
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. In addition, Brito (2000) also documented the presence of orthopyroxene. Garnet and biotite are present in the Gulçari B and Novo Amparo deposits.
Sulphides account for up to 1% of the rock in the magnetitite. The major phases are chalcopyrite and pentlandite with only very minor pyrite and pyrrhotite. Chalcopyrite is much more abundant than the other sulphides and is most common in the rock types containing 50% magnetite or less. It commonly occurs interstitially in magnetite or ilmenite enclosed by amphibole and plagioclase. Pentlandite is much less abundant and occurs in the magnetitite. The pentlandite tends to occur interstitially to the magnetite and ilmenite in silicates but, locally, composite grains of pyrrhotite, pentlandite, and chalcopyrite are enclosed in magnetite. 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.
High platinum and palladium values have been found in the magnetite 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 of 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.
It is suggested that copper, nickel and PGM were concentrated in the magnetite layers by the co- precipitation of a small quantity of sulphide with the magnetite. These PGM-bearing base metal sulphides subsequently exsolved the platinum minerals during the cumulate phase. The association of palladium minerals with base metal sulphides and the small variation in the Pt/Pd ratio (4:1) suggests that the PGMs have not been extensively remobilized in the magnetite.
The association of PGM enrichment with magnetite layers in the Rio Jacaré intrusion has similarities with the Rincón del Tigre, Skaergaard and Stella Complexes. This enrichment is rarely associated with visible sulphides, but suggests a possible new target for PGM exploration.
The Rio Jacaré intrusion hosts massive magnetite pod-like bodies confined to a layered sequence of mafic and ultramafic cumulates. They are named the lower and upper magnetite seams. The lower magnetite seam is represented by the Gulçari pod which occurs within the lower Transition zone. This zone is a 400-m-long, 150-m-thick pod tested to a vertical depth of about 350 m. It is a sequence of magnetite, pyroxenite and gabbro layers carrying vanadiferous iron ore with a mean grade of 2% V2O5 that displays PGM values up to 5 ppm Pt, 1.7 ppm Pd and an average grade of 400 ppb total PGMs.
Magnetite layers are interbedded with ultramafic and mafic cumulates. The ultramafic cumulates are transgressive towards the contact with the Lower zone gabbros and consist of olivine- magnetite cumulates, and clinopyroxene-magnetite heteradcumulates. The massive magnetite layers are made up of ilmenite-magnetite heteradcumulates that form 2 cm to 3 m thick layers containing variable amounts of clinopyroxene. Associated mafic cumulates are rhythmically micro-layered gabbro, magnetite, and magnetite-pyroxenite bands.
The outer contacts of the magnetite pods exhibit hornblende-rich rocks and dunite in places. These features are suggestive of a zoned pattern that Brito (1984) interpreted as similar to the magnetite pipe-like bodies of the Bushveld Complex. The upper Transition zone pod-like magnetite bodies are groupings of magnetite seams and pyroxenites that form 150-m long, 20-m thick masses of vanadiferous iron ore with mean grade of 0.5% V2O5 and maximum total PGM contents of 1.3 ppm and mean grade of 380 ppb. The upper Transition zone also contains a lowgrade copper sulphide mineralization which is confined to the lowermost layers of the upper magnetite seams.
In the Maracas area the water table generally lies 30 m below surface. Below this the rocks are generally fresh and above they weather and oxidize to varying degrees. Most of the weathered and oxidized material is residual. The rock types weather and oxidize in place. Locally there is lesser fluvial and colluvial material. What influences the weathering and oxidation to varying degrees are features such as faults that provide a conduit for fluid migration and enhance oxidation to depth.
The oxide minerals in this environment such as magnetite and ilmenite oxidize to other minerals such as maghemite, hematite, goethite and other iron oxides. Magnetite is strongly magnetic whereas ilmenite is moderate to weakly magnetic. The oxidized mineral maghemite is moderately magnetic and hematite, goethite and other iron oxides are weakly to non-magnetic.
Vanadium in this environment is in a plus 3 valence state, the same as the Fe+3 in the oxide minerals and substitutes for it in the magmatic process for the emplacement of the Rio Jacaré Sill. In the oxidized material that results from weathering, the vanadium stays with this Fe2O3 molecule in the oxidized minerals.
Summary:
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.
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.
The Mine Design or Pit Design, consists of projecting, based on an optimal pit, an operational pit that allows for the safe and efficient development of mining operations. The methodology consists of establishing an outline of the toes and crests of the benches, safety berms, work sites and mining site access ramps while adhering to the geometric and geotechnical parameters that were defined. The assumptions that were adopted for the operationalization of the final pit shells for each period of mining were:
• Minimize the ore mass loss;
• Define the access routes to attain shorter average transport distances.
Mine Design Parameters:
- Two Lane Ramp Width - 15m;
- Ramp Grade - 10%;
- Bench Face Angle - 85 degrees;
- Pit Slope - 60 degrees;
- Final Wall Bench Height - 20m;
- Ore Intermediated Height Bench - 5m;
- Waste Intermediated Height Bench - 10m;
- Berm Width - 5m.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
Cone crusher
|
|
|
|
2
|
Ball mill
|
|
13' x 26'
|
2.275 kW
|
1
|
Summary:
Crushing and Grinding
The ore is crushed via a three-stage crushing circuit comprising a primary jaw crusher, a secondary cone crusher and a vibrating sizing screen. The fine crushed product is fed to a 4,200- m³-capacity stockpile from which it is withdrawn at a controlled rate to feed the grinding circuit. The grinding mill grinds to a product size of minus 150 microns.
Milling
This step of processing uses a ball mill in a closed circuit with hydrocyclones. The mill dimensions are 13x26’, with 2.275 KWh (3.000 HP). The hydrocyclnes are comprised of 4 (four) Cavex 500 with 2 (two) operating and 2(two) in standby.
The mill works with maximum ball size of 90mm (Magoteaux), with a consumption of 250 g/t.
Processing
- Filter press plant
- Agitated tank (VAT) leaching
- Magnetic separation
- Mechanical evaporation
- Roasting
Flow Sheet:
Summary:
The Maracás vanadium recovery plant was commissioned in 2015 and has been in startup mode for much of that time ramping up to near design capacity. At the time of writing this report, the plant produces up to 9,360 t of V2O5 equivalent per year with a trend approaching design capacity. Except for unanticipated downtime and subject to completion of the two expansions contemplated herein, production is expected to reach 13,200 t/a V2O5 in 2020.
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, AMV calcining, and fusing to V2O5 flake as final product.
Overall recovery from ore for V2O5 is expected to reach 76% over the life of mine.
Magnetic Separation
The vanadium is contained within the magnetite fraction of the resource. Magnetite is recovered by using low intensity ........

Recoveries & Grades:
Commodity | Parameter | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
V2O5
|
Recovery Rate, %
| ......  | ......  | 77 | 75.7 | 85 | 72 |
V2O5
|
Head Grade, %
| ......  | ......  | 2 | 1.9 | 1.8 | 1.75 |
Production:
Commodity | Product | Units | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
V2O5
|
Flake & Powder
|
t
| ...... ^ | ......  | ......  | 9,830 | 9,297 | | |
V2O5
|
Flake
|
t
| | | | | | 7,966 | 5,810 |
^ Guidance / Forecast.
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Operational Metrics:
Metrics | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
Annual production capacity
| ......  | ......  | 12,000 t of v2o5 flake | | 9,634 t of v2o5 flake | 9,634 t of v2o5 flake |
Ore tonnes mined
| ......  | ......  | 1,156,016 t | 822,795 t | 1,165,950 t | 1,044,767 t |
Waste
| ......  | ......  | 7.01 Mt | 5,919,961 t | | |
Plant annual capacity
| ......  | ......  | 960,000 t | | | |
Annual processing capacity
| ......  | ......  | 1,900,000 t | | | |
Tonnes milled
| ......  | ......  | | 784,470 t | 771,804 t | 768,763 t |
Daily production capacity
| ......  | ......  | | | 26.4 t of v2o5 flake | 26.4 t of v2o5 flake |
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Reserves at October 10, 2021:
A cut-off grade of 0.3% V2O5 head is applied in V2O5 Mineral Resource.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
15.64 Mt
|
Titanium dioxide
|
8.02 %
|
1,002,650 t
|
Proven
|
15.64 Mt
|
V2O5
|
1.22 %
|
156,686 t
|
Probable
|
2.21 Mt
|
Titanium dioxide
|
8.22 %
|
151,610 t
|
Probable
|
2.21 Mt
|
V2O5
|
1.02 %
|
17,677 t
|
Proven & Probable
|
17.85 Mt
|
Titanium dioxide
|
8.04 %
|
1,154,260 t
|
Proven & Probable
|
17.85 Mt
|
V2O5
|
1.2 %
|
174,363 t
|
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Aerial view:
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