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1. Gold ore types and pretreatment
Main gold ore types:
Placer gold ore: Direct extraction through gravity separation.
Rock gold ore (Carlin type/volcanic type/iron cap type): requires a combined process of crushing-grinding-ore dressing.Pretreatment process:
Placer gold ore: ore washing → desludging → gravity separation.
Rock gold ore: three-stage crushing (jaw crusher + cone crusher + impact crusher) → ball milling → classification.
Ⅱ. Comparison of the five major gold extraction technologie
| Methods | Applicable ores | Recovery rate | Core advantages | Limitations |
|---|---|---|---|---|
| Cyanide method | High-grade gold ore (Au:Ag>5:1) | 85%~95% | Mature technology, low cost | High environmental risk |
| Carbon-in-pulp process (CIP/CIL) | Oxide ore, mud ore | 90%~98% | No need for solid-liquid separation, high activated carbon adsorption efficiency | Large equipment investment |
| Resin-in-pulp process | Complex polymetallic ore | 88%~93% | Strong wear resistance, no organic pollution | Poor adsorption selectivity |
| Flotation method | Sulfide ore, fine-grained gold | 80%~90% | Can enrich a variety of metals | High reagent cost |
| Gravity separation | Placerous gold, coarse-grained gold | 70%~85% | No chemical pollution, simple operation | Low recovery rate for fine gold |
Ⅲ. Detailed explanation of key technologies
1. Cyanidation method
Process:
Grind the ore to -200 mesh → Leach with sodium cyanide solution (48~72 hours).
Zinc powder replacement precipitation → Electrolytic purification.
Optimization direction:
Use ozone oxidation to replace cyanide (environmentally friendly process).
2. Carbon-in-Pulp Method (CIP/CIL)
Core differences:
CIP: leaching first and then adsorption, suitable for high-grade ores.
CIL: leaching and adsorption are synchronized, suitable for low-grade ores.
Equipment: High-efficiency desorption electrolysis system can reduce energy consumption by 30%.
3. Gravity separation
Equipment selection:
Jigging Machine: Processing particle size 0.04~50mm, recovery rate>80%.
Shaking table: Sorting 0.037~3mm fine gold, the concentrate grade increased by 5 times.
Spiral chute: Low-cost processing of 0.03~0.6mm ore.
Ⅳ. Practical suggestions for improving recycling rates
Combined process:
Rock gold ore: gravity pre-selection + flotation + cyanidation (recovery rate increased by 15%).
Placer gold ore: spiral chute + shaking table (fine gold recovery rate > 90%).
Equipment upgrade:
The ball mill uses rubber lining, which doubles its lifespan.
The flotation machine is equipped with a microbubble generator, which reduces the amount of reagents used by 20%.
