The Filo del Sol project will be developed as an open-pit mine. Credit: maggee/
The updated pre-feasibility study of the project was released in February 2023. Credit: Filo Corp.
The Filo del Sol project is estimated to have a proven and probable reserve of 259.6 million tonnes. Credit: yangtak/

The Filo del Sol project is an open-pit copper, gold and silver mine in the Atacama region of Chile.

Filo Mining, a Canadian exploration company and a member of the Lundin Group, is the owner and developer of the project.

An updated pre-feasibility study for the project was announced in February 2023.

The life of mine (LOM) is estimated to be 13 years, with initial capital costs projected at $1.8bn.

Location of the Filo del Sol project

The Filo del Sol project is located in the Atacama region of northern Chile. It is situated 140km south-east of Copiapo and spans the border between Argentina and Chile. The project encompasses a total area of 13,575ha.

Geology and mineralisation of Filo del Sol

Filo del Sol is a high-sulphidation epithermal copper-gold-silver deposit linked to a significant porphyry copper-gold system. It is located within the Andean Frontal Mountain Range in the Vicuna belt.

The mineralisation occurs in Late Cretaceous clastic rocks, mafic dykes, and sills, as well as in the underlying rhyolitic volcanic rocks that form part of the Permo-Triassic basement.

Reserves at Filo del Sol

The proven probable reserves at the Filo del Sol project are estimated to be 259.6 million tonnes (mt) graded at 0.39% copper, 0.34% gold and 16% silver, as of February 2023.

The total contained copper, gold and silver are estimated to be 2.2 billion pounds, 2.86 million ounces (moz) and 133.33moz, respectively.

Mining method

The Filo del Sol deposit is a large near-surface and bulk mineable deposit. It will be mined using conventional open-pit methods with a life-of-mine strip ratio of 1.57:1.

Two pit areas are proposed to be developed including the larger, multi-phase Filo pit in the north and the smaller, single-phase Tamberias pit in the south.

Mining operations are slated to begin in the Filo pit, which will be developed in four phases. The Tamberias pit will serve as an in-pit stockpile to manage ore feed gaps during the sequencing of the higher-grade Filo pushbacks.

Ore and waste will be drilled, blasted and loaded using diesel hydraulic face shovels and front-end loaders in 12m benches. Haul trucks will transport the material to the ore crusher.

The mine will implement autonomous haulage to capitalise on the technology’s proven ability to improve productivity and reduce operational costs.

Ore processing

Run-of-mine (ROM) ore will be crushed in a primary jaw crusher. The crushed output will be conveyed to a vibrating double-deck secondary screen. Oversized material from the secondary screen will be further crushed by a secondary cone crusher.

The crushed ore will be reclaimed from the stockpile and transferred to an on/off heap leach pad where the copper will be leached in sulphuric acid. The pregnant leach solution (PLS) will be pumped to the solvent extraction plant and then undergo electrowinning to produce copper anodes. Copper sheets will be stripped from the anode and prepared for export.

The ore will then be rinsed, neutralised and removed from the leach pad by a bucketwheel conveyor before being mixed with cement in the agglomerator and stacked on the permanent cyanide leach pad where gold and silver will be leached in a cyanide solution.

The Merrill Crowe zinc precipitation process will be used to treat the pregnant gold leach solution to recover gold and silver and then smelted to produce the final dore product.

Site infrastructure

The project will include the upgrade of 48km of light vehicle road to a 9m-wide, two-lane, dirt road to connect the mine site to the national highway system at Iglesia Colorada.

The site will receive electricity through a 127km-long, 110kV, single-circuit power transmission line connected to the Los Loros substation in Chile.

Water will be sourced from local aquifers in Argentina, near the proposed plant site.

The construction and operations workforce at Filo del Sol will reside in an accommodation camp, planned to be situated in Chile approximately 6.5km west of the pit. The camp is designed to house approximately 250-300 people.

Contractors involved

Ausenco Engineering Canada, an engineering firm, was responsible for preparing the PFS and managing the PFS-level design and cost estimation work for the process plant and general site infrastructure.

AGP Mining Consultants, SRK Consulting, Knight Piesold, Advantage Geoservices, and Merlin Geosciences were also involved in preparing the PFS for the Filo del Sol project.