Gramalote is a gold development project located in central Colombia. The project is 100% owned by Canada-based B2Gold.
The company released a positive Preliminary Economic Assessment (PEA) for the Gramalote Project in June 2024. The PEA results indicate that the Gramalote Project has the potential to become a medium-scale, low-cost, open pit gold mine.
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It is estimated to have an initial life of mine (LOM) of ten years, with mill processing extending to 12.5 years (Life of Project).
The project is expected to produce 185,000 ounces of gold per year. In the initial five years, average annual gold production will be approximately 234,000 ounces per year.
Pre-production capital cost was estimated to be $807m, including around $93m for mining equipment and $63m for contingency.
B2Gold is expected to complete a feasibility study on the gold project by mid-2025.
Gramalote Project Location
The Gramalote Project is situated in central Colombia in the Province of Antioquia. The site is around 230km northwest of the Colombian capital of Bogota and 100 km northeast of city of Medellin.
It lies in the Nus River valley, a highway transportation corridor connecting Bogota and the city of Medellin to the Magdalena River at Puerto Berrio. The mine can be accessed by paved roads from Medellin and Bogota.
Background
The Gramalote project was held by a joint venture between B2Gold and mining company AngloGold Ashanti.
In January 2020, B2Gold announced positive results from the Updated PEA for the Gramalote Ridge deposit within the project. The announcement was made after B2Gold assumed the role of manager of the Gramalote joint venture.
The two partners planned a large-scale project at site. However, the plan was abandoned after preliminary results completed in 2022 failed to meet the joint investment return criteria.
B2Gold subsequently signed a purchase agreement to acquire AngloGold’s 50% stake in the Gramalote project to become the sole owner of the property.
Geology and Mineralisation
The gold project is located in the northern portion of Central Cordillera in Colombia. The site features a metamorphic basement complex and the Antioquia Batholith.
The Antioquia Batholith’s compositional types are identified as tonalite and granodiorite, with subordinate monzonite and gabbro.
The two deposits on the project- Gramalote Ridge and Trinidad deposits, are categorised as structurally-controlled, intrusive-related gold deposits.
Gramalote Ridge deposit, with dimensions 1,500m by 700m, hosts mineralisation in uniform medium-grained tonalite with minor amounts of granodiorite and aplite dykes.
Mineralisation at the deposit has been drill tested to a depth of about 600m. Primarily, it comprises pyrite and chalcopyrite, with secondary minerals containing rutile and a titaniferous mineral.
Free gold is also available as argentiferous gold.
The Trinidad deposit, stretching 1,500m by 500m, contains mineralisation in similar rock types. Mineralisation at the deposit has been drill tested to a depth of about 300m.
Gramalote Project Mineral Resource Estimate
Gramalote Project includes Indicated Mineral Resources of 192.2 million tonnes grading 0.68g/t gold for a total of 4.21 million ounces of gold and Inferred Mineral Resources of 85.4 million tonnes grading 0.54g/t gold for a total of 1.48 million ounces of gold.
Mining and Ore Processing
The PEA outlined an open pit mining operation at the property that will recover up to approximately 97,000 tonnes per day (tpd) (35.3 Mtpa).
The 2020 technical report, which was based on mining of the Gramalote Ridge deposit, predicted a conventional open pit truck and shovel operation.
A waste rock storage facility (WRSF) towards the westernmost end of the project site.
The 2024 PEA said that the Gramalote gold project will include a 16,500tpd (6.0 Mtpa) processing plant to carry out crushing, grinding, flotation, and fine grinding of the flotation concentrate.
An agitated leaching of the flotation concentrate followed by a carbon-in-pulp recovery process will produce doré bullion.
Higher-grade ore will be processed in the initial years, while the lower-grade material will be stockpiled and will be treated at the end of the mine life.
Over its life, the project is expected to produce approximately 2.3 million ounces with an average gold recovery of 95.9%.
Key Infrastructure
A single circuit 230kV 26km-long transmission line is expected to supply power to the site via the existing Jaguas substation.
The 230kV supply will be reduced to 13.2kV for distribution across the facilities.
The gold project will have access to reliable water supply as it located in high rainfall region and in proximity to the Nus River.
Other infrastructure of Gramalote Project will include truckshop, warehouses, plant maintenance shop, support facilities and offices, accommodations camp, WRSFs and stockpiles; and a tailings management facility (TMF) among others.
