Gold Ore Grinding and Grinding Machinery
Grinding is a crucial step in gold ore processing, reducing the particle size to liberate gold particles for subsequent extraction (e.g., cyanidation, flotation, or gravity separation). The choice of grinding machinery depends on ore characteristics, throughput requirements, and economic factors.
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## 1. Stages of Gold Ore Grinding
Gold ore grinding typically involves two main stages:
– Primary Grinding (Coarse Grinding): Reduces ore from large chunks (~100mm) to smaller particles (~0.1–5mm).
– Secondary/Fine Grinding: Further reduces particles to finer sizes (~10–100 microns) for optimal gold liberation.
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## 2. Common Gold Ore Grinding Machinery
(A) Primary Grinding Equipment
1. Jaw Crusher
– Used for initial coarse crushing before grinding.
– Output size: ~10–150mm.
2. Gyratory Crusher
– Handles large feed sizes (>1000mm).
– Suitable for high-capacity operations.
3. SAG Mill (Semi-Autogenous Grinding Mill)
– Uses ore itself as grinding media along with steel balls.
– Reduces feed size from ~250mm to ~1–10mm.
– Energy-efficient for large-scale operations.
4. Rod Mill
– Uses steel rods for grinding coarse material.
– Produces
iform particle sizes (~0.5–5mm).
– Often used before ball mills.
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(B) Secondary/Fine Grinding Equipment
1. Ball Mill
– Most common fine grinder in gold processing.
– Uses steel balls to grind ore into fine powder (~75–150µm).
– Can operate wet or dry (wet preferred for gold leaching).
2. Vertical Roller Mill (VRM)
– Energy-efficient alternative to ball mills.
– Suitable for harder ores with lower moisture content.
3. Stirred Mill (Vertimill®, IsaMill™)
– Ultra-fine grinding (<20µm) using high-speed stirrers.
– Lower energy consumption than ball mills.
– Used when finer liberation is needed (e.g., refractory gold ores).
4. HPGR (High-Pressure Grinding Rolls)
– Compresses ore between two rollers at high pressure.
– Energy-efficient alternative to SAG/Ball