Gold smelting process is a complex process of converting primary gold ore or concentrate into high-purity metallic gold, which is mainly divided into three stages: ore pretreatment, extraction, and refining.
7 stages of gold ore smelting:
Gold smelting is a complex process of converting primary gold ore or concentrate into high-purity metallic gold. Gold smelting is mainly divided into seven core stages:
1.Ore pretreatment → 2. Ore dressing and enrichment → 3. Oxidation and decomposition → 4. Leaching and gold extraction → 5. Gold recovery → 6. Refining and purification → 7. Environmental protection treatment.
7 Steps of gold ore smelting process
1. Ore crushing and grinding
This step is also the rough refining of gold ore. The mined gold ore is crushed and ground to reach a suitable particle size for subsequent beneficiation and smelting operations. Crushing usually uses jaw crushers, cone crushers and other equipment, while grinding uses ball mills, rod mills, etc.
Ore dressing process
Gravity separation method: using the density difference between gold ore and waste rock, the gold ore is separated by gravity separation equipment such as chutes and shaking tables.
Flotation method: using the action of reagents to float the gold ore for separation. Commonly used flotation reagents include collectors, frothers and inhibitors.
Cyanide method: extracting gold elements from gold ore through cyanide solution, with high recovery rate and industrial application value. Cyanide leaching is to use cyanide to dissolve the gold in the ore and make the gold enter the solution through chemical reaction.
2. Ore dressing and enrichment
Pre-enrich gold minerals through physical/chemical methods to reduce the amount of subsequent processing.
| Gravity separation method (applicable to coarse gold particles) |
|
| Flotation method (applicable to sulfide ores): |
|
| Cyanide pretreatment (oxidized ores): |
|
3. Oxidative decomposition
Goal: Remove sulfide encapsulation and release fine gold (<10μm).
Process selection and operation:
Roasting oxidation
Equipment: Circulating boiling roasting furnace
Parameters:
First stage roasting: 650℃ (dearsenication)
Second stage roasting: 850℃ (desulfurization)
Product: porous roasted sand (gold exposure rate ≥90%)
Biological oxidation
Bacteria: Acidithiobacillus ferrooxidans
Key control points:
Slurry concentration: 18-22%
Oxidation tank temperature: 40-45℃
Residence time: 5-7 days
4. Gold extraction by leaching
Core process: Cyanide leaching (CIL/CIP)
Operation process:
Cyanide leaching
Agent system:
NaCN concentration: 0.03-0.15% (gradient decreasing)
Dissolved oxygen: ≥8ppm (pure oxygen introduced)
pH value: 10.5-11.0 (lime adjustment)
Adsorption recovery
Activated carbon specifications: coconut shell carbon (4×6 mesh, iodine value ≥1000mg/g)
Adsorption tower configuration: 6-stage series, countercurrent adsorption
Gold-loaded carbon grade: 3000-6000g/t
5. Gold recovery and refining
1. Desorption electrolysis
| Desorption solution | 1% NaOH + 0.2% NaCN |
| Conditions | 150℃, 0.5MPa (high pressure desorption) |
| Electrolytic deposition | stainless steel cathode, current density 200A/m² |
6. Gold ore refining
Refining methods: fire refining, wet refining, electrolytic refining, etc.
| Fire refining | separation of gold from other metals by high temperature melting |
| Wet refining | separation of gold from other metals by chemical reagents |
| Electrolytic refining: | separation of gold from other metals by electrolysis |
Refining process: crushing, grinding, ore dressing, smelting, refining, etc.
Purpose of refining: to improve the purity of gold to meet the standards for industrial or jewelry gold
7. Environmental protection treatment
1. Cyanide harmlessness
SO₂/air method:
Reaction conditions: pH=9-10, Cu²⁺ catalysis
End point control: CN⁻≤0.2mg/L
2. Tailings management
Dry storage: Concentrate to solid content ≥65%
Paste filling: Add cement (3-5%) for underground backfill