The Posse gold project is an open-pit gold mining project located on the Mara Rosa gold property in the Goias state of Brazil. Amarillo Gold Corporation is the 100% owner and developer of the project.
A definitive feasibility study (DFS) for the project was completed in June 2020. With an initial capital expenditure of approximately £117m ($145m), the Posse open-pit mine is expected to produce 84,000 ounces (oz) of gold a year over an estimated mine life of 10 years.
The construction on the Posse gold project is expected to be started in the first half of 2021 with the start of commercial production expected by the end of 2022.
Location, geology, and mineralisation
The Posse gold project is situated approximately 6km to the north of the town of Mara Rosa in the State of Goias, in central Brazil.
The total project area covers approximately 2,552ha encompassing three mining concessions and multiple exploration leases near the Posse gold property.
The Posse gold deposit is present in a regional thrust which is one of the primary dewatering conduits during the Neo-Proterozoic Brasilian orogeny. The deposit is hosted within a 50km long shear zone containing potassium alteration and gold-copper-molybdenum mineralisation of the lower order. It also features grey gneiss in the hanging wall of the fault and amphibolite, greenstone in the footwall.
The identified mineralised zone at the Posse deposit is approximately 30m in thickness and 1km in length and has a mylonitic appearance noticeable in the footwall. The deposit is characterised by high levels of sulphide mineralisation and high-intensity shearing resulting in higher-grade gold mineralisation.
Ore reserves at Posse gold project
The proven and probable reserves for the Posse gold project are estimated to be 23.8Mt, grading 1.18g/t Au and containing 902,000oz of gold.
The measured and indicated resources are estimated to be 32Mt grading 1.1g/t Au and containing 1,200,000oz of gold.
Mining and ore reserves at Posse gold project
The conventional open-pit mining method involving drill-blast-load-and-haul operations will be implemented for the Posse gold project.
The extracted ore will be loaded onto 45t trucks for transportation to a nearby processing plant capable of treating up to 2.5Mt of ore a year.
The run-of-the-mine ore will undergo crushing, milling, and will be pre-oxidised before passing through a carbon in leach (CIL) circuit for the recovery of gold through adsorption.
The recovered material will further undergo elution and regeneration, and the regenerated gold will be sent to the gold room where it will be filtered and purified using plate and frame filter presses. The final gold product produced will be packaged and trucked for shipping.
The Posse project site is accessed through an already existing access road. The electricity for the project is proposed to be supplied through a 67km-long, 138kV transmission line connecting Porangatu and the project site.
The project will also involve a water dam, accommodation building, and waste dumps.
The DFS for the project was prepared by SRK Consulting, which was also responsible for providing the mineral reserves estimate.
Aurifex was responsible for providing mineral processing and metallurgical testing services for the project.
Australian Exploration Field Services provided the mineral resource as well as geological services, while DBO Engenharia conducted the environmental studies for the project.