Gold Recovery Methods at Séguéla: Crushing, CIL & Gravity Circuit

Source: Fortuna Mining Corp (2026)
Website: https://fortunamining.com/mine/seguela-mine-cote-divoire/

Critical Data

Overview

The Séguéla Gold Mine, operated by Fortuna Mining Corp. in Côte d’Ivoire, employs a proven and efficient process plant to produce gold doré. Located in the Worodougou region, the facility commenced commissioning in late April 2023 and rapidly ramped up to achieve regular throughputs of 180 dry tonnes per hour by September 2023. The plant is designed for a nominal throughput of 1.25 Mtpa, with a metallurgical recovery of 93.5% and a target grind size of 75 µm. The significance of the Séguéla processing plant lies in its conventional yet robust flowsheet that integrates crushing, single-stage semi-autogenous grinding (SS SAG), gravity concentration, carbon-in-leach (CIL) leaching, and carbon elution with electrowinning. Operational data through late 2023 demonstrates consistently strong performance, averaging 93.5% gold recovery at a mill feed rate of 216 t/h and head grade of 2.87 g/t Au. The plant was designed with expansion in mind; future throughput increases to 1.57 Mtpa are possible by converting the SS SAG circuit to a SAG-ball mill configuration or by coarsening the grind to 106 µm. The tailings are disposed of in a high-density polyethylene (HDPE)-lined tailings storage facility. This integrated recovery method ensures maximum gold extraction while maintaining operational reliability and environmental stewardship, making Séguéla a significant contributor to Fortuna Mining’s gold production portfolio.

Key Process Stages

• Stage 1: Primary Crushing and Materials Handling – ROM ore is dumped at the pad, reclaimed by a front-end loader, and fed into a ROM bin. A mobile rock breaker handles oversize. Material passes over a vibrating grizzly; oversize reports to a primary jaw crusher, reducing to a product size P80 of 150 mm. Crushed ore is conveyed to a surge bin with 30 minutes capacity, providing buffer for the mill feed apron feeder.
• Stage 2: Grinding and Classification – The SAG mill (SS SAG, with future potential for SABC conversion) operates in closed circuit with classifying cyclones. Cyclone overflow (P80 of 75 µm) goes to pre-leach thickening; underflow returns to the mill for further grinding. A portion of underflow is directed to the gravity circuit. SAG mill availability reached 96.2% during performance testing.
• Stage 3: Gravity Recovery and Intensive Cyanidation – Cyclone underflow feeds a centrifugal concentrator via a scalping screen (+2 mm returned to mill). Semi-batch gravity concentrate is collected in a storage cone and then leached in the intensive cyanidation reactor (ICR) using 2% NaCN and 2% NaOH at elevated temperature with oxygen sparging for ~16 hours. Pregnant solution is processed in a dedicated electrowinning cell to recover gold sludge. Designed gravity recovery is 40%.
• Stage 4: Pre-Leach Thickening and CIL Leaching – Cyclone overflow passes through a trash screen to remove foreign material, then to a pre-leach thickener for solids concentration. Thickener underflow feeds one pre-leach tank and six CIL tanks. Oxygen and cyanide (0.22 kg/t NaCN) are added to maintain leaching conditions. Gold is adsorbed onto activated carbon moving counter-currently via airlifts. Leach time target is 24 hours, achieving tails solution grade of 0.01 g/m³ Au.
• Stage 5: Carbon Elution, Electrowinning, and Gold Room – Loaded carbon from the first CIL tank is acid washed (3% HCl) before elution using the split AARL process at 125°C with 2% NaCN and NaOH. Pregnant eluate is electrowon onto stainless steel cathodes. Gold sludge is dried, mixed with fluxes, and smelted in a diesel-fired furnace to produce doré bars. Carbon is regenerated in a rotary kiln at 700–750°C. The gold room includes comprehensive security systems.

Additional Interesting Data and Summary

The Séguéla processing plant incorporates several auxiliary systems critical to its performance and sustainability. Reagent handling facilities for quicklime, sodium cyanide, sodium hydroxide, hydrochloric acid, flocculant, and activated carbon are designed with 110% containment to prevent spills. Lime addition is 0.33 kg/t ore (93% CaO purity) and sodium cyanide addition is 0.22 kg/t ore. The plant is controlled by a PLC/SCADA system with fiber optic communication, and a site-wide emergency power plant has been installed. Electrical reticulation uses 11 kV and 415 V three-phase, 50 Hz power, with underground cables within the plant and overhead lines for remote areas (TSF and water storage dam). Services include high-pressure air (700 kPa) for plant and instrument air, low-pressure blowers for leach tanks, and a pressure swing adsorption oxygen plant for CIL and ICR circuits. Raw water from storage is used for fire water, filtration, and reagent make-up; potable water from treated bore water is supplied to camp and plant. Filtered water serves elution and gland water needs. Tailings are deposited in an HDPE-lined TSF with decant return water providing most process water, supplemented by raw water. The Qualified Person confirms that process requirements are well-understood, with commissioned ramp-up data validating design assumptions. The plant uses conventional technology and readily available consumables, with no anticipated changes in ore characteristics. Future expansion potential exists to increase throughput to 1.57 Mtpa via SABC conversion or grind coarsening. Environmental considerations are addressed through containment systems and lined tailings storage. The facility’s strong operational performance—exceeding crusher and mill throughput KPIs and meeting gold recovery targets—demonstrates its economic viability and sustainability. For the life-of-mine plan, processing assumptions are considered reasonable, positioning Séguéla as a reliable gold producer in Côte d’Ivoire.

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

Target Commodities: Gold