Technical report and preliminary economic assessment update for the SMSZ Project in Mali, describing a proposed modular gravity-CIL processing plant with a nominal throughput of 1200 tonnes per day.
Report context
This NI 43-101 Technical Report and PEA Update on the SMSZ Project in Mali, prepared for Desert Gold Ventures Inc., is dated December 2025. The report describes a proposed upgraded modular processing plant designed as a conventional gravity-Carbon-in-Leach (CIL) circuit with a nominal throughput of 1200 tonnes per day (tpd), representing a doubling of the original design plant capacity from 600 tpd. The plant will process oxide ore from Barani East, Gourbassi West, and Gourbassi West North, and oxide and transitional ore from the Gourbassi East deposit.
Processing route
Process overview
The upgraded modular processing plant is designed as a conventional gravity-CIL circuit at 1200 tpd nominal throughput, equivalent to approximately 36 kilo tonnes per month (ktpm) or 432,000 tonnes per annum (tpa) at steady state, assuming 92% availability. Metallurgical testwork indicates strong amenability to gravity recovery, particularly for Barani East, and CIL leaching optimal for Gourbassi ores.
The flowsheet incorporates crushing, screening, grinding, classification, thickening, CIL leaching, desorption, electrolysis and smelting, with tailings disposal via wet discharge. Gravity concentration is integrated as a pre-leaching step to remove gravity recoverable gold, based on testwork recommendations. Loaded carbon is eluted in a 1 tonne per batch Zadra pressure elution column, followed by electrowinning and smelting to produce Doré gold bars on site. CIL tailings are detoxified and pumped to HDPE-lined tailings storage facilities.
The fully skid-mounted design is intended to permit relocation within three months with minimal production loss, confirming both technical and economic feasibility for the life-of-mine across all four ore sources.
Crushing circuit
The crushing circuit reduces Run-of-Mine ore to a particle size of P80 = 13 mm through a three-stage arrangement consisting of a primary coarse jaw crusher followed by a secondary fine jaw crusher and a tertiary cone crusher operating in closed circuit with a linear vibrating screen. Design criteria specify a maximum feed particle size F100 of 480 mm for the primary crusher and a product size P80 of 112 mm. The secondary crusher product size P80 is 62 mm, while the tertiary crusher product size P80 is 14 mm. All crushers, screens, and associated conveyors are individually skid-mounted with hydraulic support legs.
Grinding and classification
Crushed ore is reclaimed to a two-stage ball milling circuit. The primary mill (3.2 m diameter x 4.5 m length, 630 kW power loading) grinds crushed ore to an intermediate P80 of approximately 212 microns, with a spiral classifier in closed circuit. Steel ball loading for the primary mill is expected to be approximately 76 tonnes.
The secondary regrind ball mill (2.4 m diameter x 4.5 m length, 400 kW installed motor power) grinds final Knelson tailings to a P90 of 75 µm to achieve optimised gold liberation for CIL leaching. It operates in closed circuit with cyclones for classification. Steel ball loading for the secondary mill is expected to be approximately 44 tonnes.
Gravity concentration
Primary mill discharge reports to two continuous-feed Centrifugal Concentrators (STL-100 type). A two-stage configuration uses a primary batch Knelson concentrator followed by a secondary Knelson CVD (continuous variable discharge) unit processing the primary Knelson tailings. Combined concentrate from the two centrifugal concentrators is upgraded on two 6-S shaking tables to produce final gravity concentrate, collected in secure bins for subsequent smelting or future intensive cyanidation. Shaking table middlings are recycled to the primary mill, while table tailings are returned to the process stream ahead of secondary milling.
Design criteria indicate a concentrate mass pull of 0.08% of feed for all ore types. Concentrate grades from testwork for the gravity circuit are reported as: Barani East 20.11 g/t, Gourbassi West/West-North 2.57 g/t.
Leaching and adsorption
Gravity tailings are thickened to 40% solids and conditioned in two tanks of 510 m³ each, providing approximately 10 hours of conditioning residence time. Leaching then takes place in seven subsequent CIL tanks of 510 m³ nominal volume each, providing 41 hours of total residence time at design tonnage. The design leach residence time specified is 24 hours, which testwork indicates is exceeded for all ore types. Cyanide concentration is maintained at 300–400 ppm, pH at 10.5–11 using lime and caustic soda, with oxygen sparging to enhance leach kinetics. Carbon concentration in slurry is 20 g/L, using coconut shell carbon. Tailings gold grades from the CIL circuit based on testwork data are reported as: Barani East 0.17 g/t, Gourbassi West/West-North 0.06 g/t, Gourbassi East 0.20 g/t.
Elution and electrowinning
Loaded carbon from the second CIL tank is acid-washed and stripped in a 1-tonne-per-batch pressure Zadra elution column equipped with electric heaters. Elution stripping temperature is 150°C. Stripped carbon passes through a regeneration kiln before being returned to the circuit. Pregnant eluate is processed in electrowinning cells using steel wool cathodes to produce gold sludge, which is subsequently filtered, dried, and smelted with gravity concentrate in a conventional tilt-pour induction furnace to produce Doré gold bars containing greater than 90% gold and silver.
Tailings management
CIL tailings first pass over safety screens to capture residual carbon before entering an agitated detoxification tank. Cyanide is destroyed using SO₂ (or process air or sodium metabisulphite) in the presence of a copper catalyst and lime, with a target weak-acid-dissociable cyanide concentration of below 50 ppm prior to discharge. Detoxified tailings are pumped to HDPE-lined tailings storage facilities, with one facility at Barani East and one central facility serving the Gourbassi cluster after plant relocation. The Barani East TSF is designed with a total volume of 190,195 m³ and total height of 10 m. The Gourbassi West/West-North TSF has a total volume of 1,286,968 m³ and total height of 20 m. The Gourbassi East TSF has a total volume of 183,614 m³ and total height of 10 m.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Nominal throughput | 1,200 tpd (432,000 tpa) | Design |
| Plant availability (milling/CIL) | 97.3% | Design |
| Crushing circuit availability | 78.1% | Design |
| Feed rate to milling/CIL | 54 tph | Design |
| Final grind size (primary mill P80) | 212 µm | Design |
| Final grind size (secondary mill P90) | 75 µm | Design |
| CIL residence time (total) | 44 hours | Design |
| CIL residence time (design leach) | 24 hours | Design |
| Conditioning tanks | 2 x 510 m³ | Design |
| Leach tanks | 7 x 510 m³ | Design |
| Cyanide consumption | 2 kg/t ore | Design |
| Caustic consumption (Barani East) | 15.57 kg/t ore | Design |
| Caustic consumption (Gourbassi W/WN) | 2.29 kg/t ore | Design |
| Elution capacity | 1 tonne per batch | Design |
| Gold recovery in gravity circuit (Barani East) | 69.49% | Testwork |
| Gold recovery in CIL circuit (Barani East) | 71.94% | Testwork |
| Gold recovery in CIL circuit (Gourbassi W/WN) | 90.34% | Testwork |
| Tailings grade (Gourbassi W/WN CIL) | 0.06 g/t | Testwork |
| Bond Ball Work Index | 10.0 kWh/t | Testwork/Design |
| Total installed power | approx. 3,058 kW | Design |
Project website: https://desertgold.ca/
Technical qualifications
The report states that no testwork was performed for KE and Keniegouloo ore types, and therefore no gravity or leaching recovery data is included for these sources. Mass balances for the gravity concentration circuit were calculated using testwork data, focusing on batch and continuous gravity separation for gold recovery. The leaching circuit mass balance was calculated using testwork data from the report's metallurgical testwork chapter. Crushing circuit mass balance was determined using simulation systems from Metso (My Plant Planner) and Sandvik Group (PlantDesigner). The installed power total of 3,058 kW excludes auxiliaries like lighting and controls, and power for minor components such as instrumentation, screens, and electrics is not explicitly listed in the quotation.
Source: Desert Gold Ventures Inc. NI 43-101 Mineral Resource Technical Report and PEA Update on the SMSZ Project – Mali, December 2025, Sections 17.1–17.3.
