Gold Ore Types & Extraction: 7 Key Processes Guide

Global geopolitical tensions, expectations of loose monetary policies by central banks, and a surge in safe-haven demand have all pushed up gold prices. In 2025, the international gold price continued to rise (breaking through $2,700 per ounce this month, up more than 20% from 2023), strengthening the status of gold as a safe asset and stimulating investment in global gold mining resources.

Gold ore is a mineral aggregate with sufficient content of gold that can be industrially utilized. Gold mines are places where gold is obtained through mining operations and are deposits of gold ore with a certain scale that can be industrially utilized formed through mineralization.

The types of gold mines are complex and diverse. This article will introduce in detail the common types of gold mines and their extraction methods.

Types of gold ore

1.Natural gold ore

• Gold exists in the form of free (natural gold) or alloys (such as silver-gold ore), often in flake, dendritic, or granular form.
• Occurs in quartz veins or tectonic fracture zones, coexisting with sulfides such as pyrite and galena.
• The gold particles are coarser (> 0.1 mm), visible to the naked eye, and can be directly recovered by reselection (such as shaking table , chute ).

Equipment	Applicable particle size	Capacity
Shaking Table	Coarse sand (0.5–2 mm), fine sand (0.074–0.5 mm), sludge (≤0.074 mm)	10–60 t/d
Spiral Chute	Fine minerals (0.02–0.3 mm)	2–40 t/h
Jig	Coarse minerals (typically >2 mm)	30–250 t/h

2. Sulphide type gold ore

• Gold is present in sulfides such as pyrite, arsenopyrite, and chalcopyrite with fine particle inclusions (< 0.01 mm).
• The ore contains harmful elements such as arsenic and mercury, and needs to be floated to enrich sulfides and then leached by cyanide.
• When the degree of sulfide development is high, the gold color is low (with high silver content).

3. Quartz vein type gold deposit

• Gold is embedded in milky or smoky quartz veins and often coexists with sulfides (such as pyrite) in a strip-like manner.
• The ore needs to be crushed to fine grains (< 75 μm) and then cyanide or thiourea leached.
• High-grade ores can be directly amalgamated for gold extraction.

4. Placer gold (alluvial type)

• Secondary deposits are enriched in riverbeds or gravel layers of ancient rivers after weathering and erosion of primary gold deposits.
• Gold is flaky or granular, with a smooth surface, often associated with heavy minerals such as magnetite and ilmenite.
• Recycling by washing, spiral concentrator or jig.

5. Carlin-type gold deposits

• Fine-grained gold (< 1μm) occurs in carbonate rocks or carbonaceous shales and is invisible to the naked eye.
• It often contains elements such as arsenic, mercury, and antimony, and requires oxidation roasting or biological pre-oxidation treatment to improve the leaching rate.
• The ore has the characteristic of “invisible gold” and needs to be detected by fire assay or electron probe.

6. Iron oxide type gold ore (IOCG type)

• Gold coexists with hematite, magnetite, and chalcopyrite and is formed in a high-temperature hydrothermal environment.
• The ore needs to be separated by magnetic separation of iron minerals and then leached by cyanide or thiosulfate.
• It is often accompanied by metals such as copper and uranium, and has comprehensive recycling value.

7. Altered rock type gold deposit (shallow low temperature hydrothermal type)

• Gold is related to silicification and sericite alteration zones and is distributed in volcanic or sedimentary rocks in a soaked manner.
• The ore grade is low (1-3 g/t) and requires heap leaching or biological leaching technology treatment.
• It often contains associated elements such as silver and tellurium, and typical minerals are glacier and kaolinite.

extraction method of gold ore

Gold ore processing refers to the process of extracting gold from gold-bearing ore. This process usually includes multiple steps such as crushing, grinding, beneficiation and chemical treatment to separate gold from other minerals and metals.

1.Re-selection method

• Applicable ores : placer gold ore, natural gold ore (coarse gold particles, > 0.1 mm).
• Principle : Use the high density of gold (19.3 g/cm ³) to separate from light minerals (quartz, gravel).
• Method : Shaker, chute, jig, spiral concentrator.
• Advantages : low cost, environmental protection; Disadvantages : only suitable for coarse-grained gold.

2.Flotation method

• Applicable ore : sulfide type gold ore (gold wrapped in pyrite, poison sand).
• Principle : Through the agent (collector, foaming agent) to make sulfide minerals adsorption bubbles float.
• Process : Flotation enrichment of sulfide concentrate → roasting/oxidation pretreatment → cyanide leaching.
• Advantages : recovery of fine gold; Disadvantages : the need for supporting leaching process, high cost.

3.Cyanidation process (CIL/CIP)

• Applicable ores : quartz vein type, oxidized gold ore (gold dissociable).
• Principle : Dissolve gold with sodium cyanide (NaCN) to form a complex (Au (CN) -2), and adsorb and recover it with activated carbon.
• Process : crushing → grinding → cyanide leaching → carbon adsorption → electrolytic purification.
• Advantages : High collection rate (> 90%); Disadvantages : Risk of cyanide contamination.

4.Amalgamation method

• Applicable ores : high-grade natural gold ore (clean surface of gold particles).
• Principle : Mercury and gold form amalgam, heat distillation separation of mercury (recovery of gold).
• Advantages : simple and efficient; Disadvantages : mercury toxicity, has been gradually eliminated.

5.Heap leaching method

• Applicable ores : low grade oxidized ore (gold occurs in cracks).
• Principle : Stack the ore, spray the cyanide solution, and collect the leachate after the gold dissolves.
• Advantages : large processing capacity, low cost; Disadvantages : long leaching cycle (several months), need to prevent leakage.

6.Biological oxidation process

• Applicable ore : refractory ore (such as carlin type gold ore, arsenic, carbonaceous package).
• Principle : Oxidation of sulfides by acidophilic bacteria (such as Thiobacillus ferrooxidans) releases gold.
• Process : bacterial oxidation pretreatment → cyanide leaching.
• Advantages : environmental protection; Disadvantages : slow reaction speed, need to control bacterial activity.

7.Thiosulfate process

• Applicable ores : ores with more copper or clay minerals (cyanide method is not applicable).
• Principle : Thiosulfate (S ² O ²) dissolves gold under alkaline conditions without cyanide contamination.
• Advantages : environmental protection; Disadvantages : large drug consumption, high cost.

8.Pyrometallurgy

• Applicable ores : complex polymetallic associated minerals (such as iron oxide type gold ore).
• Principle : high temperature melting separation of metals, gold enriched in lead or copper matte, and then electrolytic purification.
• Advantages : processing complex ores; Disadvantages : high energy consumption, waste gas needs to be purified.

Selection based on

• Gold occurrence state : coarse-grained gold (re-selection), fine-wrapped gold (flotation + cyanide).
• Mineral symbiosis : high sulfide content requires pretreatment, arsenic/carbonaceous needs biological oxidation.
• Environmental requirements : priority biological method or thiosulfate method to avoid cyanide/mercury pollution.

Typical process examples

1. Quartz vein oxidized ore : crushing → grinding → gravity dressing (recovery of coarse-grained gold) → tailings cyanide → carbon adsorption → electrolytic gold extraction.
2. Sulfide-containing primary ore : flotation → concentrate roasting → cyanide leaching → zinc powder replacement.
3. Fine-grained impregnated ore : ultrafine grinding → biological pre-oxidation → cyanide → resin adsorption.

Trends in technological development

• Environmental protection : gradually replace cyanide process, promote thiosulfate, biological leaching and other green technologies.
• Efficiency : Combining microwave, ultrasonic and other physical fields to strengthen the leaching process.
• Intelligent : Optimize sorting parameters through automatic mineral analysis to reduce energy consumption and losses.

Different ores need to be determined by mineralogical analysis (XRD, XRF, etc.) to determine the best process, and priority should be given to mineral processing tests to optimize the process