The entire dataset was subject to independent revision and auditing by Millcreek Mining Group, which signed off on the new resource statement for the project. Aguia claims that the resource estimate meets the necessary criteria to comply with both JORC and NI 43-101 standards.
The mineral resource statement is based on the results of a drilling campaign that Aguia carried out between December last year and June this year. Over the course of the period, the company completed 61 core holes (9708 m) and 90 reverse circulation holes (4496 m). The main aim of the campaign was to increase the geologic assurance and classification of the inferred resources identified in the 2016 resource statement related to the Três Estradas project. Aguia claims that the drilling campaign was successful in converting most inferred resources in the 2016 resource estimate and measured and indicated categories as well as discovering and delineating additions to the Três Estradas deposit, including a new extension to the deposit.
83 million t grading 4.1% P2O5 of measured and indicated resources are now included in the mineral resource statement. Therefore, 79% of the current resource model is in the measured and indicated category. The previous model, on the other hand, only comprised 21% of measured and indicated resources.
As well as a high rate of conversion of inferred resources to measured and indicated resources, Aguia claims that the mineral resource statement also identified a new shallow zone of mineralisation within the Três Estradas pit shell’s existing borders.
With a resource that is 41% larger, Aguia has the option of selecting a higher cut-off grade as feedstock for the planned operation. Subject to the completion of the bankable feasibility study (BFS), which is currently on going, this is expected to have an output of 300 000 tpy of phosphate concentrate.
The main differences between the estimate presented in 2016 and the current mineral resource statement are as follows:
- The 2016 estimate identified 15.07 million t of measured plus indicated resources at a P2O5 grade of 4.75% using a 3.0% cut-off. The new estimate, meanwhile, identifies 83.2 million t of measured plus indicated resources at 4.11% P2O5 grade using a 3.0% cut-off. Inferred resources have fallen from 58.9 million t to 21.8 million t in the mineral resource statement.
- Tighter estimation parameters have been implemented in the mineral resource statement.
- Rock density values have been incorporated into the block model versus the usage of average density values for each of the mineralised domains.
- The mineral resource statement in 2016 included resources for the Joca Tavares deposit. There has not been any further work carried out at Joca Tavares and resources from the deposit are not included in the current mineral resource statement.
Fernando Tallarico, Technical Director, said: “After an extensive drilling campaign we are very excited by this outcome. Not only were we able to expand the global resource, but the current 83 million t of measured and indicated resources is bigger than the global resource we reported previously. This resource expansion together with the exceptional conversion rate to Measured and Indicated categories will allow important optimizations of the mining plan, including choices of higher cut-off grades of the run of mine that ultimately we expect will improve the production costs of the project.”
Justin Reid, Managing Director, added: “The drilling program was expanded due to excellent results. Not only have we had a very high conversion rate from Inferred to measured and indicated resources, the identification of the new limb in the southeast zone has allowed us to add to the resource within the existing pit borders. The results we have now prove that this is a high quality, consistent phosphate asset that will now form the basis for the BFS which is laying out the development plan for the Três Estradas project. The option of an increased cut-off grade means we will mine the highest-grade, lowest strip, most profitable rock. I am optimistic this will result in a material impact to our overall mining costs and calculated strip-ratio as we finalise the ultimate mine plan.”