Gold Ore Extraction Technology: Three-Stage Efficient Recovery Solution

Mineralogical characteristics of oxidized gold ores

Gold does not exist in the form of oxides in nature due to its inert chemical properties. The so-called oxidized gold ore actually refers to gold-bearing deposits transformed by surface oxidation, and its characteristics are as follows:

1. Mineral composition: mainly iron oxides such as limonite and hematite, with a small amount of quartz and residual sulfide

2. Occurrence: gold particles are mainly embedded in the cracks of goethite/limonite or wrapped in weathering and alteration minerals

3. Physical properties: typical yellow to brown appearance, loose and porous structure, good permeability

Three-stage gold extraction process

Stage 1: Ore pretreatment and crushing

1. Raw material preparation: Use drum screen to remove clay (pre-drying is required when moisture content is greater than 15%)

2. Multi-stage crushing system:

- Primary crushing: jaw crusher (feed size ≤800mm, discharge size ≤150mm)

- Secondary crushing: cone crusher (discharge size ≤50mm)

- Tertiary crushing (optional): high pressure roller mill (discharge size ≤20mm)

3. Screening control: Configure double-layer vibrating screen (upper screen size 25mm, lower screen size 8mm)

                       

Phase 2: Grinding for optimal dissociation

                       

The third stage: combined application of sorting processes

1. Gravity separation

Gravity separation is a physical method that uses the difference in specific gravity between gold ore and gangue minerals for separation.

Commonly used oxidized gold ore gravity separation equipment includes shaking table, spiral chute, jig, etc.

Shaking Table: It has a low processing capacity but is suitable for small to medium-sized dressing plants requiring high sorting accuracy. It handles fine gold ore and is simple to operate with low cost.

Spiral Concentrator: Ideal for large-scale operations, it has a high processing capacity, efficiently handling medium to fine gold ore with continuous, stable performance.

Jig: Used for coarse gold ore separation. It has high processing capacity and is suitable for large-scale initial separation or roughing.

2. Cyanide leaching system

- Agitation cyanidation (applicable to -0.074mm accounting for more than 90%):

* Parameter control: NaCN concentration 0.03-0.1%, pH 10.5-11.0, dissolved oxygen 6-8ppm

* Carbon-in-Pulp (CIP) adsorption rate ＞99%

- Heap leaching process (ore particle size 5-20mm):

* Heap height 4-8m, spray intensity 5-15L/m²·h

* Precious liquid gold grade 0.5-5g/t, total recovery rate 60-85%

3. Combined process scheme

- Partially oxidized ore: gravity separation-cyanidation combination (recovery rate increased by 8-12%)

- Completely oxidized ore:

* Coarse particle size (+0.5mm) → Shaking table separation

* Fine particle size (-0.5mm) → Stirring cyanidation

* Intermediate particle size → Percolation cyanidation (leaching cycle 5-15 days)

Technical and economic comparison