A ball mill is a crucial piece of equipment in gold ore processing, used to grind the ore into fine particles for further extraction. Below is a detailed overview of its application in gold mining:
1. Purpose of a Ball Mill in Gold Ore Processing
– Grinding: Reduces gold-bearing ore into fine powder (~75 microns or finer) to liberate gold particles.
– Preparation for Cyanidation/Leaching: Finer particles increase surface area, improving gold recovery rates.
– Consistency: Ensures uniform particle size for efficient downstream processing.
2. Types of Ball Mills Used in Gold Mining
– Wet Ball Mill: Most common for gold ore; operates with water to form a slurry, preventing dust and aiding in grinding.
– Dry Ball Mill: Less common but used when water is scarce or for specific ore types.
– Grid/Overflow Discharge: Determines how ground material exits the mill.
3. Key Components
– Rotating Drum: Filled with steel balls (grinding media) and ore.
– Liners: Protect the drum from wear (rubber, manganese steel, or ceramic).
– Drive System: Motor, gearbox, and pinion to rotate the drum.
– Feed/Discharge Hoppers: For loading ore and removing ground slurry.
4. Operating Parameters
| Parameter | Typical Range |
|———–|————–|
| Speed | 65–80% of critical speed |
| Ball Charge | 20–35% of mill volume |
| Feed Size | <25mm (after crushing) |
| Discharge Size | 75–150 microns (varies by process) |
5. Grinding Media (Balls)
– Material: High-chrome steel, forged steel, or ceramic.
– Size: 20–100mm (selected based on ore hardness and target grind size).
.jpg)
6. Gold-Specific Considerations
– Free-Milling vs. Refractory Ore:
– Free-milling ores (easy to liberate gold): Standard ball milling suffices.
– Refractory ores (gold locked in sulfides): May require finer grinding (<45 microns) or pre-treatment (e.g., roasting/flotation).
– Recovery Optimization: Over-grinding can lead to slimes that hinder leaching; controlled milling is key.
7. Integration with Gold Processing Circuit
1. Crushing → M
Leave a Reply