This report details the metallurgical recovery methods, infrastructure, and key parameters of the Obuasi Mine's South Process Plant as described in the 2023 technical report.
Report context
The Obuasi Mine, located in Ghana, is an operating gold mine. The 2023 Technical Report, with an effective date of 31 December 2023, outlines a life-of-mine (LOM) plan supported by existing infrastructure. The process plant, known as the South Process Plant, is central to the mineral processing and recovery strategy. The report describes the metallurgical flowsheet, its design basis, historical modifications, and planned future improvements based on additional metallurgical testwork.
Processing route
Flowsheet overview
The South Process Plant is designed around a metallurgical flowsheet intended to achieve optimum recovery while minimizing operating costs. The flowsheet utilizes unit operations well proven in industry. The processing methods incorporated include:
- Crushing
- Ore handling
- Coarse and fine grinding
- Gravity separation
- Flotation
- Thickening
- BIOX (biological oxidation)
- Neutralisation
- CIL (carbon-in-leach)
- Tailings and water management
Design and historical operation
The plant is designed to achieve a steady-state throughput of 180,000 tonnes per month (t/month), equivalent to 6,000 tonnes per day (tpd). Since operations commenced, the plant has undergone several stages of modification, expansion, and reconfiguration.
Notable historical changes include:
- Addition of unit processes, specifically flash flotation and gravity separation.
- Discontinuation of other processes, particularly the CIL circuit that previously treated flotation tailings.
The LOM plan assumes that the process plant flowsheet will be further modified to improve recoveries. This is contingent upon additional metallurgical testwork being performed on other ore blocks. The report states that the assumptions on processing route and recovery are appropriate for the mineralisation based on data acquired from comprehensive ore tests.
Utilities and water supply
The process plant receives its electrical power from the National Grid, with an on-site emergency generator providing backup during outages. Water for processing activities is sourced from underground. River water is treated at the site's potable water treatment plants to ensure a safe drinking water supply.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Design steady-state throughput | 180,000 t/month (6,000 tpd) | Design |
| Gold price – Mineral Reserve estimation | $1,400/oz | Management-determined |
| Gold price – Mineral Resource estimation | $1,750/oz | Management-determined |
| On-site emergency generator capacity | 20 MW | Infrastructure |
Project website: https://www.anglogoldashanti.com/portfolio/africa/obuasi/
Technical qualifications
The report notes that no market studies are currently relevant, as the Obuasi Mine is an operating mine producing a readily-saleable commodity (doré). The metallurgical flowsheet is based on assumptions that are considered appropriate for the mineralisation, based on data from comprehensive ore tests. However, the LOM plan explicitly anticipates further flowsheet modifications to improve recoveries, dependent on the outcome of additional metallurgical testwork on other blocks. Specific recovery rates or metallurgical performance figures are not disclosed in the provided material.
Source: AngloGold Ashanti NI 43-101 Technical Report Obuasi Mine, Ghana – effective date 31 December 2023.
