Rio Grande Projects

Rio Grande Projects

Aguia’s Rio Grande assets are located in the state of Rio Grande do Sul in Southern Brazil. The Rio Grande Deposits consist of the Três Estradas, Joca Tavares, and Porteira carbonatite-hosted phosphate and the Cerro Preto sediment-hosted phosphate. These deposits are located in a farming region some 350 km from the State Capital Porto Alegre. The region is well serviced by roads, rail, port and power.


  • Aguia Resources is focused on developing the sole source of domestic phosphate supply for the fertilizer market in southern Brazil
  • JORC/NI 43-101 compliant resource with 36Mt Measured Mineral Resources @ 4.01% P2O5, 47Mt Indicated Mineral Resources with an average grade of 4.18% P2O5 and 21.8Mt Inferred Mineral Resources with an average grade of 3.67% P2O5 using a minimum cut-off grade of 3.0% P2O5 (1)
  • Simple open pit with infrastructure in place; rail, road, power, town, regional fertilizer blenders
  • Team in place to take Três Estradas through to production
  • Bankable Feasibility completed March 2018
  • Approval of Environmental Impact Assessment and granting of LP (Preliminary License) imminent
  • Final community consultation meeting as part of LP (Preliminary License) on 20 March 2019 – no further community consultation required
  • New copper discovery identifies extensive zone (9km x 3km) of mineralization proximal to past production in Camaqua Copper Belt

Três Estradas

Aguia’s Três Estradas project is located in the state of Rio Grande do Sul, Southern Brazil in a major farming region which imports 100% of its phosrock requirements. There are currently no phosphate mines in the region and none scheduled to be built in the foreseeable future other than Aguia’s planned development of Três Estradas. Três Estradas is the most advanced of Aguia’s holdings in the region   Aguia has also signed option agreements on a number of neighbouring properties which are currently being explored.

The Três Estradas Audited Mineral Resource identifies 83 million tonnes of measured and indicated material with an average grade of 4.1% P2O5 using a cut-off grade of 3.0% of P2O5. The estimate also identifies 21.8 million tonnes of inferred material with an average grade of 3.67% P2O5. By classification, 79% of the resources contained within the optimized pit shell are measured and indicated with the remaining 21% of the resource classified as inferred resource.(1)

(1) Três Estradas Phosphate Project’s 2017 Mineral Resource Statement, Rio Grande do Sul, Brazil, Millcreek Mining Group, September 8, 2017. Mineral Resources are not mineral reserves and have not demonstrated economic viability. All figures are rounded to reflect relative accuracy of the estimates. The mineral resources are reported within a conceptual pit shell using a cut-off grade of 3.0% for all mineralized domains. Optimization parameters include a mining recovery of 100%, 0% dilution, process recovery of 87% P2O5 for saprolites and 80% P2O5 recovery for fresh rock, concentrate grade of 35.0% for saprolite and 32.0% for fresh rock, pit slopes of 34° for saprolite/51° & 55° for fresh rock, selling price of US$215 for P2O5 concentrate and exchange rate of 3.2 R$ to US$.

Domain Volume
(m3 x 1000)
(T x 1000)
P2O5 CaO% P2O5 as
Apatite (%)
CaO as
Calcite (%)
Total Measured Resources 12,975 36,196 2.82 4.01 33.59 9.5 59.95
Total Indicated Resources 17,671 47,014 2.74 4.18 31.72 9.91 56.63
Total Measured + Indicated
30,646 83,210 2.77 4.11 32.53 9.73 58.07
Total Inferred Resources 7,605 21,845 2.88 3.67 33.62 8.69 60.01
Classification Reserves
(Saprolite, tonnes)
(Carbonatite + Amphibolite,tonnes)
Head Grade
(% P2O5
Proven 844,302 27,023,619 27,867,921 3.92
Probable 4,352,915 11,334,168 15,687,083 5.01
Proven +
5,197,217 38,357,787 43,555,004 4.31

The Proven and Probable Mineral Reserves are included in Measured and Indicated Mineral Resources.

Aguia engaged Eriez Flotation Division (Pennsylvania, US) to run a pilot-plant testing for flotation, which was backed-up with a recent comminution study by Metso. A multi-month study, using bulk samples and performed at Eriez’s pilot-plant facilities in Pennsylvania, USA, has confirmed the earlier bench-scale work, as well as further improvements in the process design to improve grade – recovery projections. The current findings and conclusions from the most recent pilot-plant program and collector reagents optimization testwork are as follows:

  • For the saprolite ore, global phosphate recovery of 81.4% is achievable at a concentrate grade of 32.7% P2O5;
  • For the carbonatite ore, global phosphate recovery of 75.3% is achievable at a concentrate grade of 30.1% P2O5Metallurgical studies also confirm the presence of a high quality calcite by-product which may have the potential to add a secondary revenue stream to the Três Estradas deposit in the event production is achieved in the future. From the rougher tailing of the phosphate flotation, a calcite concentrate grading 48.55% CaO was produced with a CaO recovery of 83.1%. Due to a high reactivity, the calcite is suitable as a high quality aglime to be spread on fields to reduce acidity and meets the specifications of the cement industry, animal nutrition market and to neutralize sulphur in thermoelectric plants.

The Três Estradas project contemplates an open-pit, truck and shovel operation, over a life of mine of 16 years plus an additional 20 years of aglime production from reclaimed tailings, totalling 36 years of operation.

With an average capacity of 300,000 tpy of phosrock the average annual feed to the processing plant will be 1.3 million tonnes of the oxide ore in Phase 1 ,and 3.3 million in Phase 2 of the fresh carbonatite ore, resulting in a life of mine production of 4.7 million tonnes of phosphate concentrate and another 32.9 million tonnes of aglime, averaging about 300,000 tons of phosrock annually over 16 years and one million tonnes of by-product aglime annually over 33 years. The relatively steeply dipping and confined nature of the deposit, as well as the drive to optimize project value through early development of the saprolite ore, leads to a decreasing strip ratio after Year 4.

Três Estradas is located in a predominantly farming region with proximity to local infrastructure including roads, a rail line through the property and power. Major fertilizer blenders are located just 200km away at Porto Alegre.