Overview
The Mercedes Mine processing facility employs conventional milling with Merrill-Crowe precious metal recovery, capable of processing approximately 2,000 tonnes per day (tpd). The plant features a comprehensive circuit including three-stage crushing, grinding, cyanide leaching, CCD washing, and specialized recovery systems for gold and silver extraction.
Key Process Stages
- Three-Stage Crushing: Primary jaw crusher (89mm product), secondary cone crusher (19mm product), and tertiary cone crusher (9.5mm product) with screening between stages
- Grinding & Classification: Single 5.03m x 8.84m ball mill (3,430 kW) in closed circuit with 254mm hydrocyclones, achieving P80 of 45µm
- Leaching: Four 9.3m x 9.9m agitated tanks with 24-hour retention time at 50% solids
- CCD Circuit: Four 16.4m diameter thickeners for solution recovery
- Merrill-Crowe Recovery: Zinc dust cementation process handling 155,000 oz gold and 595,000 oz silver annually
- Tailings Treatment: INCO SO2-air cyanide detoxification in two 7.5m x 8.5m reactors
- Refining: Retort furnaces for mercury removal and diesel-fired smelting to produce doré bars
Critical Data
| Parameter | Value |
|---|---|
| Design Throughput | 2,000 tpd |
| Primary Crusher Power | 112 kW |
| Secondary/Tertiary Crusher Power | 224 kW each |
| Ball Mill Power | 3,430 kW |
| Fine Ore Bin Capacity | 3,500 tonnes live (5,275 total) |
| Leach Retention Time | 24 hours |
| Annual Gold Recovery Capacity | 155,000 oz |
| Annual Silver Recovery Capacity | 595,000 oz |
| Detoxification Retention Time | 1.5 hours per tank |
Recent Optimization
In 2021, plant modifications were implemented to recirculate cyanide-containing solution from the CCD circuit to the grinding circuit, reducing overall cyanide consumption while maintaining recovery efficiency.
