Mining Operations

Cordero Mine

The Cordero Mine is part of the Company’s El Bagre Gold Mining Complex. Development of the Cordero mine began in September of 2020 and commercial production was achieved as of January 1, 2023. Soma’s legacy mines, La Ye and Los Mangos, were mined out and are being decommissioned in early 2023.  Going forward, Cordero will be supplying the mill feed for the El Bagre Mill and, as mine production warrants, the restart of the Limon Mill.  This should have a significant positive impact on gold production, as La Ye and Mangos ore has averaged ~4.5 g/t gold in recent years, while Cordero’s resources are grading 6.9 g/t and 7.9 g/t for indicated and inferred resources, respectively.

The production rate of 84 thousand tonnes (kt) in 2022 is scheduled to ramp up to a peak mining production rate of 248 kt (680 tpd) in 2024. Achieving the planned peak production rate of 248 kt per annum would allow the Company to restart its previously operating El Limon Mill, with feed from Cordero in late 2024.

Based on the PEA results, Cordero’s current Life of Mine (LOM) plan is just over three years, ending in early 2026. However, our current drill program, with both surface and underground drilling underway, is anticipated to add new resources to materially extend Cordero’s mine life.

Soma has purchased a fleet of Sandvik underground mining equipment and is now self-performing all mining and sustaining development work.

The Cordero mine is proposed to be approximately 1,280 m on strike and 300 m deep, with veins dipping from 30 degrees to 45 degrees. The LOM plan envisions a mixture of both conventional and mechanized mining. In the central portion of the Mineral Resource area, mining will be carried out by a narrow, near-vertical, non-mechanized cut-and-fill mining method.  Production work in this area is done by teams using pneumatic handheld drilling equipment. Mechanized overhand cut-and-fill mining is planned for the deeper north-south extents of the Cordero mine, using equipment owned and operated by Soma. The introduction of mechanized mining will allow Soma to materially increase production and mill throughput to warrant restarting the El Limon Mill.

Geology of the Cordero Deposit

The Cordero Deposit is hosted in the El Carmen Stock, an early Carboniferous-age tonalite to diorite intrusive that occurs along the western boundary of the Segovia Batholith. Gold mineralization in the Carmen Stock is hosted in shear zone-controlled quartz veins that strike north-northwest and dip moderately to the northeast in the Cordero and Los Mangos mines. In contrast to the eastern deposits, quartz veins in the La Ye Mine notably have a northerly strike and dip steeply to the west. Gold mineralization in the quartz-carbonate veins is associated with pyrite, galena, sphalerite tellurides, and locally free gold. The deposit is cross-cut by two phases of younger mafic dykes, which are subsequently cross-cut by a young, felsic aplite dyke suite. The younger dykes are interpreted to be Jurassic-age or younger.

Exploration and in-fill drilling continue through 2024 at the Cordero Deposit (Cordero). A total of 10,000 meters of underground and surface drilling is planned for Cordero.

Milling Operations

El Bagre Mill

Soma’s El Bagre Gold Mining Complex is located approximately 167 km north-northeast of Medellín in the Department of Antioquia, Colombia. Soma produced 32,340 ounces of gold at its El Bagre Mill in 2023 – an increase of 40% from the previous year.  Soma’s production forecast for 2024 is for 30,000 ounces of gold produced.

Gold production will be driven by:

  • Increased throughput from mechanized mining at the Cordero Mine
  • Higher average gold grades as our legacy La Ye and Mangos Mines are mined out, and substantially all 2024 ore will be sourced from our higher-grade Cordero Mine.

The El Bagre Mill processes approximately 450 tonnes per day (tpd) when running at full capacity and is permitted for up to 1,000 tpd.  The mill historically achieves gold recoveries of ~87% and silver recoveries of ~81%. Initiatives in 2023 increased gold recovery to 88% and further plant modifications are intended to bring the recovery rate to 90% by EOY 2024.

The plant consists of the following main circuits:

  • Three-stage crushing
  • One-stage grinding
  • Flash coarse rougher flotation in the grinding circuit
  • Gravity concentration and intensive cyanide leaching
  • Flotation, thickening, and clarification
  • Regrinding and cyanidation
  • Filtration and cyanide detoxification
  • Merrill Crowe gold recovery
  • Smelting
  • Reagent preparation
  • Tailings disposal

El Limon Mill

In addition to its operating El Bagre Mill, Soma owns the 225 tpd Limon Mill, which is located 47 km south of the El Bagre Mill. The Limon Mill has been on care and maintenance since 2020 but will be restarted when production from the Cordero Mine exceeds the capacity of the El Bagre Mill.

The Limon Mill operates similarly to the El Bagre Mill with two-stage crushing, ball milling, gravity concentration, flotation, cyanidation, Merrill Crowe precipitation, and smelting to produce doré. The mill was upgraded in 2017 to a capacity of 225 tpd and is permitted for up to 400 tpd.

Soma has formalized agreements with three of the (formerly illegal) small miners near the El Limon Project and anticipates formalizing additional miners in the future. This allows them access to modern mining and processing technologies, including eliminating the need to use mercury to extract gold. It is anticipated that these small miners will provide some of the feed for the El Limon mill when it is restarted.