B2Gold has announced positive results from an updated preliminary economic assessment (PEA) of the Gramalote Ridge deposit at the Gramalote gold project in Antioquia province, Colombia. The project is a joint venture between B2Gold and AngloGold Ashanti. B2Gold assumed the role of manager of the joint venture on January 1.
Assuming an effective date of January 1 and a gold price of $1,350 per ounce (oz), Gramalote Ridge economic highlights include an open-pit gold mine with an initial mine life of 13.6 years based on current indicated and inferred mineral resources for the Gramalote Ridge deposit only. Life-of-mine gold production is estimated at 3.85 million oz, including an average of 416,600 oz per year (oz/y) during the first five full years of production.
Average life-of-mine all-in sustaining costs are estimated at $648/oz of gold produced. Preproduction capital costs are estimated at $901 million, including approximately $160 million for mining equipment.
Accelerated mining is planned for the early years of operation to provide higher-grade feed to the plant while stockpiling lower-grade material. The final four years of plant feed are from low-grade stockpiles and oxide ore. Oxide ore, which only makes up about 3% of the plant feed, will be stockpiled and processed at the very end of the project life, as blending this material with fresh ore does not yield optimal gold recoveries.
Processing is planned to include crushing; grinding; flotation, with fine grinding of the flotation concentrate; agitated leaching of both the flotation concentrate and the flotation tails; and carbon-in-pulp recovery to produce doré bullion. Plant throughput is planned at 11 million mt/y. Gold recovery is estimated at 94.3%.
B2Gold is currently completing approximately 42,500 meters (m) of infill drilling at Gramalote Ridge to convert existing inferred mineral resources to indicated and 7,645 m of geotechnical drilling for site infrastructure. The mineral resource estimate that forms the basis for the PEA includes indicated mineral resources of 70.1 million metric tons (mt) grading 0.92 grams/mt gold for a total of 2.07 million oz of gold and inferred mineral resources of 79 million mt grading 0.79 g/mt gold for a total of 2.01 million oz of gold.
The PEA is based solely on production from the Gramalote Ridge deposit and does not include potential production from the nearby Trinidad deposit or the Monjas West zone.
B2Gold and AngloGold Ashanti have budgeted approximately $37 million for a feasibility study of the Gramalote project, with completion of the study expected by the end of 2020. Feasibility work will include completion of all planned drilling by the end of May 2020, an updated mineral resource estimate, detailed mine planning, ongoing environmental studies, additional metallurgical test work, engineering, and detailed economic analysis.