Cerro del Gallo Heap Leach & SART Gold-Silver-Copper Recovery

Source: Heliostar Metals Ltd (2026)
Website: https://www.heliostarmetals.com/projects/development/cerro-del-gallo/

Critical Data

Overview

Heliostar Metals Ltd. is advancing the Cerro del Gallo Project (CdG) in Guanajuato, Mexico, a gold-silver-copper deposit amenable to heap leaching. The Pre-Feasibility Study (PFS) effective December 11, 2025, outlines a robust recovery flowsheet integrating state-of-the-art crushing, agglomeration, heap leaching, a SART plant, and a carbon adsorption-desorption-recovery (ADR) circuit. The ore is mined by conventional open-pit methods and processed at a nominal rate of 16,667 tonnes per day. A three-stage crushing system incorporating a primary jaw crusher, secondary cone crushers, and a high-pressure grinding roll (HPGR) achieves a final product size of 80% passing 4–6 mm. The crushed ore is agglomerated with cement and conveyor-stacked in 8-meter lifts on a 92-million-tonne capacity lined heap leach pad. The heap is irrigated with dilute sodium cyanide solution in two phases: 40 days at 12 L/h/m² and 80 days at 6 L/h/m², for a total leach cycle of 120 days. Pregnant solution containing gold, silver, and copper is treated in a SART plant, where copper and silver are precipitated as sulfides for sale as a filter cake, and the regenerated cyanide is recycled. Gold is recovered from the SART barren solution via carbon adsorption, desorption, electrowinning, and smelting to produce doré bars. This integrated approach maximizes metal recovery, reduces cyanide consumption, and generates additional revenue from the copper-silver precipitate, making Cerro del Gallo a technically and economically significant project.

Key Process Stages

• Stage 1: Three-Stage Crushing – Run-of-mine ore is dumped into a 200-tonne feed bin, passes a vibrating grizzly, and is crushed by a primary jaw crusher (open circuit, 80% passing 145 mm). The product is stockpiled, then reclaimed and conveyed to secondary crushing using two double-deck vibrating screens and two cone crushers in closed circuit (80% passing 36 mm). Tertiary crushing employs an HPGR in closed circuit with triple-deck vibrating screens to produce a final product of 80% passing 4–6 mm. Design capacities: nominal 16,667 t/d (696 t/h), design 22,200 t/d (925 t/h).
• Stage 2: Agglomeration and Stacking – Fine ore is reclaimed and conveyed to two parallel agglomeration drums, where cement (added from silos controlled by weightometers) and barren process solution are blended. The agglomerated ore discharges onto a stacking system comprising an overland conveyor, up to 23 mobile grasshopper conveyors, and a radial stacker. Material is placed in 8-meter lifts on the leach pad. The pad is constructed in four phases with a composite liner (clay/GCL and textured HDPE geomembrane) covering 139.8 hectares with a maximum heap height of 80 meters.
• Stage 3: Heap Leaching – Irrigation uses drip tubes with dilute sodium cyanide solution (approx. 1500 ppm CN). Leaching occurs in two stages: Phase 1 (first 40 days) at 12 L/h/m², Phase 2 (next 80 days) at 6 L/h/m². Barren solution is pumped at a nominal 1,280 m³/h (design 1,400 m³/h) from a barren tank via two horizontal centrifugal pumps. Antiscale agent is added. Pregnant solution is collected in the pregnant solution pond via a network of perforated drainage pipes and pumped to the SART circuit. Total leach cycle: 120 days.
• Stage 4: SART Plant – Pregnant solution is acidified with sulfuric acid, then sodium hydrosulfide is added to precipitate copper and silver as sulfides. The precipitate is thickened and filtered to produce a copper-silver filter cake sold to a smelter. The SART process releases cyanide from copper-cyanide complexes, allowing it to be recycled as free cyanide back to the leach circuit, reducing overall cyanide consumption. Gypsum slurry by-product is managed in a lined Gypsum Pond (2-year capacity).
• Stage 5: ADR Plant and Gold Recovery – Barren solution from SART is processed in a carbon adsorption-desorption-recovery (ADR) circuit. Gold is adsorbed onto activated carbon, periodically stripped using a desorption process, then electrowon onto stainless steel cathodes. The gold deposit is washed, filtered, dried, and smelted to produce doré bars. The ADR plant is designed to handle the full 1,400 m³/h flow from the SART circuit, ensuring efficient gold recovery with minimal losses.

Additional Interesting Data and Summary

The Cerro del Gallo heap leach facility is designed to process approximately 92 million tonnes of ore over its life, with a maximum heap height of 80 meters across 139.8 hectares. The pad is constructed in four phases with a composite liner system meeting Nevada Administrative Code 445A.434 and Mexican Standard NOM-155-SEMARNAT-2007. The liner consists of a 1.5-mm textured HDPE geomembrane over a 300-mm compacted soil liner (or GCL) and a 700-mm drainage layer overliner with minimum permeability of 1×10⁻¹ cm/sec. Solution collection uses perforated pipes (100–450 mm diameter CPE) maintaining a maximum hydraulic head of 0.7 m on the liner. The SART plant produces a copper-silver sulfide filter cake for sale, adding revenue while reducing cyanide consumption. Gypsum slurry from SART is stored in a double-lined pond (2-year capacity). A detailed pre-feasibility water balance accounts for average as-mined moisture, 1,280 m³/h nominal leach application, and evaporation; the barren tank has negligible storage. The Waste Rock Dump stores 30.3 Mt (of 33.3 Mt total) with dry density 1.9 t/m³. Stormwater diversion channels are sized for a 1-in-100-year, 24-hour event. Environmentally, the double-lined pregnant and event ponds provide secondary containment and leak detection, while underdrain systems capture spring water and seepage. The project operates 360 days per year, with crushing at 75% utilization (18 h/day). Future outlook includes phased leach pad expansion (Phases 2–4) without additional equipment, progressive reclamation of the WRD, and monitoring of gypsum for alternative disposal. The integrated heap leach–SART–ADR circuit positions Cerro del Gallo as a model for sustainable precious and base metal recovery in Mexico, with potential to reduce environmental footprint through cyanide recycling and co-product sales.

Key Processes: Heap Leaching, Cyanidation, Gravity Separation, Crushing

Target Commodities: Gold, Silver, Copper