This technical report presents the updated mineral resource estimate and processing framework for the Bibiani Gold Mine, Ghana, as at 31 December 2023.
Report context
The Bibiani Gold Mine is owned and operated by Mensin Gold Bibiani Limited, a wholly owned Ghanaian subsidiary of Asante Gold Corporation. The effective date of this technical report is 31 December 2023, with an issue date of 30 April 2024. The Ghanaian Government holds a 10% non-equity free carry interest in the mine. This report supersedes the earlier NI 43-101 Technical Report with effective date 28 February 2022.
Processing route
Overall process design
The Bibiani processing plant is a 3.0Mtpa refurbished conventional carbon-in-leach (CIL) milling and processing facility. The plant achieved approximately 85% gold recovery during the 2022 to 2023 operating period. A phased expansion to 4.0Mtpa is planned from 2026. A schematic process flowsheet indicates current and phased additions, including a future flotation circuit and concentrate regrind, as well as an intensive concentrate leach and adsorption circuit.
Phase 1A plant modifications
Phase 1A modifications to the existing conventional CIL circuit included installation of a crusher, a PSA oxygen plant, and a Mach shear reactor. These modifications were completed before the 2022 plant start-up. Plant operations performance data for Phase 1A show the impact of the oxygen plant and online Mach reactor on peroxide consumption and dissolved oxygen levels. Dissolved oxygen levels were recorded before and after Mach reactor installation. The CIL tank 1 dissolution rate and dissolved oxygen levels were also monitored. Phase 1A milled tonnes per month versus plant availability and pit ore blend are documented.
Phase 1B key process design criteria
Phase 1B key process design criteria were sourced from Lycopodium 1997 and from Mining Process Project Engineering 2021. The schematic flowsheet of the future flotation circuit includes concentrate regrind, and the intensive concentrate leach and adsorption circuit is shown separately.
Key reported parameters
| Parameter | Value | Unit | Basis |
|---|---|---|---|
| Plant capacity (current) | 3.0 | Mtpa | Design (refurbished) |
| Plant capacity (planned) | 4.0 | Mtpa | Proposed design from 2026 |
| Gold recovery (conventional CIL, 2022-2023) | ~85 | % | Actual operating data |
| Main Pit sulphide ore treatment overall recovery (declared) | 92.0 | % | Testwork (2015 ALS variability) |
| Russell Pit sulphide ore treatment overall recovery (average normalised) | 90.2 | % | Testwork (2023 Intertek preliminary) |
| Main Pit high-grade sample sulphide flotation+leach recovery | 93.1 | % | Testwork (2023 Intertek preliminary, no gravity) |
| Main Pit high-grade sample direct cyanide recovery (P80 75µm) | 86.6 | % | Testwork (2023 Intertek preliminary, no gravity) |
| Main Pit variability CIL on gravity tails (average) | 71.5 | % | Testwork (2015 ALS Phase 2) |
| Main Pit gravity recovery (average, 14 variability samples) | 34 | % | Testwork (2015 ALS Phase 2) |
| Main Pit ALS variability overall gold recovery (range) | 85.1 – 92.6 | % | Testwork (2015 ALS, normalised, no gravity) |
| Main Pit ALS variability overall gold recovery (average) | 89.1 | % | Testwork (2015 ALS, normalised, no gravity) |
Project website: https://www.asantegold.com/operations/bibiani
Technical qualifications
The metallurgical test work reported for the Main Pit and Russell Pit is described as preliminary. The two Main Pit composite samples taken from stockpiles by geologists are noted as not representative of the ore body. A gravity gold recovery step was not included in the 2015 ALS Phase 1 and Phase 2 variability test work, and the declared 92.0% overall recovery for Main Pit sulphide ore treatment includes an additional 2.9% for the excluded gravity extraction step. The 2023 Intertek test work programs also did not include gravity gold recovery tests. The report states that the 2015 ALS test work results have been used as definitive for this study.
Source: NI 43-101 Technical Report and Updated Mineral Resource Estimate, Mensin Gold Bibiani Limited, Ghana, West Africa, effective 31 December 2023, issue date 30 April 2024, Sections 13, 17.
