La Mina Project: Gold-Copper Flotation and CIL Recovery

Source: GoldMining Inc (2026)
Website: https://www.goldmining.com/projects/colombia/la-mina-project/

Critical Data

Overview

GoldMining Inc., through its Preliminary Economic Assessment (PEA) effective April 22, 2026, outlines a robust gold-copper recovery process for the La Mina Gold-Copper Mineral Deposit located in the Department of Antioquia, Republic of Colombia. The proposed processing facility is designed to handle 15,000 tonnes per day (tpd) of mineralized material sourced from the La Cantera, Middle Zone, and La Garrucha open pits. This conventional yet advanced flowsheet integrates primary crushing, grinding, and copper flotation to produce a high-grade copper concentrate containing gold and silver as valuable by-products. The flotation tailings then undergo cyanide carbon-in-leach (CIL) treatment to recover additional gold and silver, which are refined into doré bars on-site. The process is supported by a dedicated team of 128 process department employees and achieves a nominal circuit availability of 92%. The PEA demonstrates the economic viability of the La Mina Project, though it remains preliminary in nature. The recovery methods are designed for maximum efficiency, with careful attention to environmental stewardship through cyanide detoxification and a lined tailings storage facility. This integrated approach ensures that the La Mina Project can deliver a premium copper concentrate to third-party smelters while maximizing precious metal recovery, positioning GoldMining Inc. as a promising player in the Colombian mining sector.

Key Process Stages

• Stage 1: Primary Crushing and Coarse Stockpile – ROM material from open pits is fed into a gyratory crusher, followed by a cone crusher for secondary reduction to a nominal 38 mm 80% passing size. Crushed material is conveyed to a stockpile for downstream grinding.
• Stage 2: Grinding Circuit – The grinding circuit consists of a 9.8 m diameter x 3 m long 5.0 MW SAG mill in open circuit, followed by a 5.8 m diameter x 12.0 m long 8.0 MW ball mill in closed circuit with hydrocyclones. The target grind size is 80% passing 130 µm. Pebble crushers handle SAG mill screen oversize, and lime is added for pH control.
• Stage 3: Flotation Circuit – Cyclone overflow at ~35% solids enters two conditioning tanks for collector and frother addition. Rougher flotation uses eight 120 m³ cells, followed by scavenger flotation with eight 120 m³ cells. Rougher and scavenger concentrates are reground in a 1,675 kW regrind ball mill to 30 µm. Cleaner stages, including two flotation columns, produce a final concentrate grading approximately 23% Cu, 75.8 g/t Au, and 144.2 g/t Ag at pH 11.0 to depress pyrite.
• Stage 4: Copper Concentrate Thickening and Filtration – Second cleaner concentrate is thickened in a high-rate thickener, with overflow recycled as process water. Underflow is dewatered using pressure filters to approximately 8% moisture. Filter cake is stored for truck shipment to a third-party smelter; filtrate returns to the process water tank.
• Stage 5: Preaeration, CIL Leach, Gold Adsorption, and Refining – Scavenger tailing thickener underflow (45–48% solids) feeds two 19 m x 19 m pre-aeration tanks with compressed air for sulfide oxidation (12-hour residence). Slurry then enters eight 19 m x 19 m CIL tanks in series with activated carbon (35 g/L). Gold and silver are adsorbed over 48-hour residence. Loaded carbon is acid washed, stripped using hot alkaline solution in electrowinning cells, and reactivated in a rotary kiln. Electrowinning sludge is dried and melted in a furnace to produce doré bars for off-site refining.

Additional Interesting Data and Summary

The La Mina Project’s recovery methods are underpinned by a comprehensive process plant infrastructure designed for operational efficiency and environmental responsibility. The plant will employ 128 personnel across management, assay, metallurgy, maintenance, and operations, reflecting a strong commitment to skilled labor and quality control. Key reagents include flotation collector, frother, milk-of-lime, flocculant, anti-scalant, sodium cyanide, and cyanide detox reagent, all stored and handled according to industry best practices. Process water is primarily recycled from the tailings storage facility (TSF) and internal circuits, minimizing freshwater demand. The TSF is lined to prevent groundwater contamination, and cyanide detoxification tanks (two 19 m x 19 m agitated vessels with ~12-hour retention) ensure residual cyanide levels meet acceptable limits before tailings deposition. The process plant’s service systems include fresh water, potable water, fire suppression, flotation blowers, pre-aeration and CIL compressors, and instrument air. Economically, the production of a high-grade copper concentrate (23% Cu) with significant gold and silver credits enhances project revenue, while doré bars offer additional precious metal value. The PEA is a preliminary assessment; Inferred Mineral Resources are considered too speculative to convert to reserves, and there is no certainty the projected economic performance will be realized. However, the robust process design—from gyratory crushing to final doré refining—demonstrates GoldMining Inc.’s technical capability. Future development will likely focus on optimizing reagent consumption, improving recovery rates, and advancing environmental monitoring. Overall, the La Mina Project presents a well-integrated gold-copper recovery scheme that balances metallurgical performance with sustainable practices, positioning it as a significant potential contributor to Colombia’s mining sector.

Key Processes: Flotation, CIP/CIL, Cyanidation, Gravity Separation, SAG Mill, Ball Mill, Crushing

Target Commodities: Gold, Silver, Copper