Filo Mining has released the results of a prefeasibility study, carried out by Ausenco, on its Filo del Sol copper-gold-silver project on the borders of Chile and Argentina.
The PFS envisages average annual production of approximately 67,000 t of copper, 159,000 oz of gold, and 8.65 Moz of silver at a C1 cost of $1.23/lb ($2,712/t) copper-equivalent.
It also contemplates the use of an autonomous haul truck fleet, which allows the company to take advantage of the technology’s proven productivity improvements and operating cost savings, Filo Mining said.
Filo Mining is the second development-focused company in the past few months to make plans to incorporate autonomous haulage from the off. In November, NGEx Resources said it assumed its Josemaría project in Chile would use the latest in autonomous haul truck technologies.
The Filo del Sol study contemplates open-pit mining, with conventional drilling, blasting and loading performed on 12 m benches and is based off an initial probable reserve of 259 Mt at 0.39% Cu, 0.33 g/t Au and 15 g/t Ag.
Pre-production capital was pegged at $1.27 billion (excluding costs prior to a construction decision) and the company estimated a 14-year mine life with copper cathode, gold-silver doré and a high-grade copper precipitate produced. Filo said the post-tax net present value (8% discount) was $1.28 billion at copper, gold and silver prices of $3.00/lb, $1,300/oz and $20/oz, respectively.
Filo del Sol hosts a high-sulphidation epithermal copper-gold-silver deposit associated with a large porphyry copper-gold system. The project is in the Andes Mountains on the border of Chile and Argentina, approximately 140 km southeast of the city of Copiapó.
From the open pit, ore would be trucked to a conventional two-stage crusher, designed to process 60,000 t/d of ore. Crushed ore would be treated by sequential heap leaching, to extract copper and subsequently gold and silver from the ore followed by hydrometallurgical processing to produce copper cathodes and gold-silver doré. A portion of the barren leach solution, following zinc precipitation, would be treated to avoid a build-up of recirculating copper and cyanide through the gold circuit. This treatment is based on the SART process, which produces a copper sulphide precipitate (with grades of around 65% Cu) and recovers cyanide for use in the heap leach.
Groundwater for the process plant would be supplied from nearby aquifers to the plant site, and power would come from a 127 km of power line construction to connect to the Chilean national grid.
The PFS was prepared and managed by Ausenco Engineering Canada, with input from AGP Mining Consultants, BGC Engineering, Knight Piésold, Advantage Geoservices Limited, Merlin Geosciences and SRK Consulting.