INV Metals has announced positive results from an independent, updated feasibility study of its 100% owned Loma Larga gold-copper-silver project in south-central Ecuador, about 480 kilometers (km) south of Quito. Life-of-mine production of payable metals in separate gold pyrite and gold-copper concentrates over a 12-year mine life is forecast at 1.61 million ounces (oz) of gold, 8.87 million oz of silver, and 58.84 million lb of copper.
The feasibility study identifies Loma Larga as a low-cost operation, with expected life-of-mine all-in sustaining costs of $627/oz. Initial preproduction capital expenditures are estimated at $316 million, with sustaining capital of $71 million and closure costs of $22 million, including taxes and duties.
Loma Larga has proven and probable reserves of 13.9 million metric tons (mt) grading 4.91 grams (g) per mt gold, 29.6 g/mt silver, and 0.29% copper, containing 2.2 million oz of gold, 13.27 million oz of silver, and 88 million lb of copper.
The underground mine will be accessed by a 1.2-km-long ramp, 5 m high by 5 m wide, that will serve as the access to the mine for personnel and materials, haulage of waste and ore, and ventilation. Due to the high-grade nature of the orebody and positive geotechnical conditions, the deposit will primarily be mined by long-hole stoping, with stopes 20 m long by 20 m wide by 25 m high. Some zones will utilize drift-and-fill mining where appropriate.
Ore production of 3,000 mt/d is planned from primary and secondary stopes for the first four years, generating approximately 1 million mt/y of ore. From year 5, daily average ore production will increase to 3,400 mt/d through plant optimization, and plant throughput will increase to about 1.24 million mt/y.
Ore will be processed using primary and secondary crushing, a ball mill, and a two-stage sequential flotation circuit to recover gold, silver, and copper into two separate saleable concentrates that will be trucked to port for export.
Overall gold, silver, and copper recoveries into concentrate are estimated at 90%, 95%, and 96%, respectively.