This technical report describes the proposed processing plant configuration for oxide and transitional ores from the Barani East, Gourbassi West, and Gourbassi West North deposits.
Report context
The report, dated August 2025, presents a preliminary economic assessment for the SMSZ Project in Mali. The processing section details a proposed single modular circuit design for 18.0 ktpm throughput, processing oxide and transitional ores in two phases: initially at Barani East (Years 1–3) and subsequently relocated to Gourbassi West and West North (Years 4–17).
Processing route
Proposed plant design
The final processing plant will be a single modular circuit designed for 18.0 ktpm (approximately 25 tph at 92% availability). The unified circuit accommodates metallurgical differences between ore types with tailored recovery efficiencies and includes scrubbing of run-of-mine ore to remove clay and fines, producing a coarse fraction and fines below 2 mm; two-stage crushing and screening of scrubbed ore to produce material with 80% passing 10 mm; primary milling of the minus 10 mm feed down to 212 µm; secondary milling of coarse slurry down to 75 µm; classification via cyclones in closed circuit; thickening of classified slurry to 40% solids; conditioning with cyanide and lime for carbon-in-leach (CIL) processing; conventional CIL processing with loaded carbon sent to elution; elution and electrowinning; smelting of electrowinning sludge combined with gravity concentrates to produce doré bars; and detoxification of CIL tailings for deposition in a lined tailings storage facility with water recycling.
Proposed phase operations
The single circuit is applied in two phases. The first phase at Barani East (Years 1–3) is designed to process 530 kt of ore at 1.67 g/t Au, yielding approximately 31.2 koz of gold at approximately 74% recovery. The report notes that CIL addresses moderate preg-robbing yielding approximately 72% recovery from testwork despite higher sulphide content. The second phase relocates the plant to Gourbassi West and West North (Years 4–17) to process 3,117 kt of ore at 0.83 g/t Au, yielding approximately 91.3 koz of gold at approximately 91% recovery, where CIL consistently achieves over 90% recovery due to the free-milling nature of the ore.
Upside potential for gravity recovery
An upside potential for recovery, specifically for Barani East, would be to include a gravity recovery step. The report states that Barani East will benefit from up to 69.5% of the available gold being recovered as a preliminary step, with CIL handling the remaining. The circuit would consist of primary gravity recovery via a batch Knelson and secondary gravity recovery with a Continuous Variable Discharge Knelson unit. Both concentrates will be upgraded with a Gemini Shaking Table before smelting. This would increase the overall gold recovery for the first 3 years to 92% as supported by testwork, if the grade can be controlled accordingly. Gourbassi West and West-North has a low overall gravity amenability for the ore at around 20% average which gives minimal benefit from the gravity circuit, with an estimated 1% increase in overall gold recovery and low smelting potential.
Historical operating data
No historical operating data is presented in the report. The processing description is based on proposed design criteria and testwork results.
Testwork basis
The report references metallurgical testwork supporting recovery estimates. For Barani East, CIL yields approximately 72% recovery from testwork, while gravity recovery testwork supports potential overall recovery of 92%. For Gourbassi West and West North, testwork shows CIL consistently achieves over 90% recovery. Mass pull values for the CIL mass balance were derived from recent testwork.
Key reported parameters
| Parameter | Units | Value | Basis |
|---|---|---|---|
| Plant throughput | ktpm | 18.0 | Design |
| Plant throughput (operating) | tph | 25 at 92% availability | Design |
| Annual RoM treatment rate | tpa | 216,000 | Design |
| Crushing circuit availability | % | 78.08 | Design |
| Milling and CIL circuit availability | % | 94.52 | Design |
| RoM feed size F80 | mm | 315 | Design |
| Primary mill product P80 | µm | 212 | Design |
| Secondary mill product P80 | µm | 75 | Design |
| Primary ball mill installed power | kW | 630 (725 installed) | Design |
| Secondary ball mill installed power | kW | 26 (30 installed) | Design |
| CIL conditioning residence time | h | 1.45 (Barani East), 1.48 (Gourbassi West) | Design |
| CIL leach residence time | h | 6.22 (noted as too short) | Design |
| Barani East: ore processed (Years 1–3) | kt | 530 | Proposed |
| Barani East: head grade | g/t Au | 1.67 | Proposed |
| Barani East: gold recovery (CIL only) | % | ~72 (testwork), ~74 (design) | Testwork/Design |
| Barani East: gold recovery (with gravity) | % | 92 | Testwork |
| Barani East: gold production | koz | ~31.2 | Proposed |
| Gourbassi West/West North: ore processed (Years 4–17) | kt | 3,117 | Proposed |
| Gourbassi West/West North: head grade | g/t Au | 0.83 | Proposed |
| Gourbassi West/West North: gold recovery | % | ~91 | Testwork |
| Gourbassi West/West North: gold production | koz | ~91.3 | Proposed |
| CIL tank volume (each) | m³ | 80 | Design |
| Number of CIL leach tanks | No. | 5 | Design |
| Carbon concentration in slurry | g/L | 20 | Design |
| Elution column capacity | kg | 600 (540 actual loading) | Design |
| Cyanide dosage | kg/t ore | 2 | Design |
| Doré bar gold purity | % | >90 | Design |
| Total installed power (big-ticket items) | kW | ~1,025.5 | Design |
Project website: https://desertgold.ca/
Technical qualifications
The report notes that the CIL leach residence time of 6.22 hours is too short for sufficient leaching, with an estimated 10% to 30% loss in recovery. It is advised to increase residence time by adding tanks or choosing bigger CIL tanks from the beginning.
The report states that the crushing circuit mass balance was determined utilising Metso My Plant Planner simulation software, with confirmation from Sandvik PlantDesigner. The thickener design was verified against testwork settling rates for water recovery estimates.
The process description is based on a preliminary economic assessment and does not constitute a feasibility study. The proposed gravity circuit for Barani East is identified as an upside potential subject to grade control.
*Source: Desert Gold Ventures Inc. NI 43-101 Mineral Resource Technical Report and PEA on the SMSZ Project – Mali, August 2025, Sections 17 Recovery Methods.*
