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2025 Gold Extraction Guide–Gold Ore and Refining Methods

What is gold ore?

What does gold ore look like? Gold ore refers to ore containing gold elements, which is a type of metal ore. Gold is a precious metal because it is chemically stable and will not oxidize, corrode or decay. The value of gold lies not only in its beauty, but also in its rarity and historical value. There are relatively many types of gold ores, and the gold content in the ores varies greatly. The gold extraction and beneficiation methods of different types of gold ores will also be different.

В этой статье, Smat will introduce you to 8 common gold ores and 11 methods of gold ore extraction.

11 types of gold ore

1. Natural gold ore

Natural gold refers to unprocessed gold found on the surface or underground of the earth. Natural gold usually exists in the form of gold grains or gold nuggets in ores, and can also be found in riverbeds, beaches or mineral deposits. The identification method of natural gold is to judge by appearance and weight. The color of natural gold is usually golden yellow, and sometimes gray, silver or black. Natural gold has a high density and is heavier than most rocks and ores, so it can be judged by weight whether it is natural gold.

2. Quartz Vein Gold Ore

The gold in Quartz Vein Gold Ore is present in quartz veins as natural gold (Au) particles. It is often formed in medium-low temperature hydrothermal environments and is related to magmatic activity. It is accompanied by a small amount of pyrite and arsenopyrite. The gold particle size ranges from coarse (>0.1 мм) to fine (<50 μm). Known gold mines include the Witwatersrand Gold Mine in South Africa and the Xiaoqinling Gold Mine in China.

Ore dressing technology: гравитационное разделение (встряхивающий стол, желоб) + cyanide gold extraction.

3. Sulfide Gold Ore

Sulfide Gold Ore Gold is encapsulated in sulfide minerals such as pyrite (FeS₂) и арсенопирит (FeAsS). It is mostly formed in medium-low temperature hydrothermal environments and is related to volcanic activity and magma intrusion. It is commonly found in volcanic rock areas and some metamorphic rock areas.

Mining methods: flotation and cyanidation are usually used, and sometimes gravity separation is also used.

4. Orogenic Gold Ore

Orogenic gold mines are mainly composed of minerals such as quartz, полевой шпат, and mica, and gold exists in these minerals in the form of microparticles. They are formed during the orogenic movement and are related to regional metamorphism and tectonic activities. They are widely distributed in orogenic belts around the world, such as the Alps and the Himalayas.

Ore dressing methods: mainly cyanidation and flotation.

5. Placer Golden oreos

The mineral composition of placer gold mines is mainly composed of gold and some heavy minerals. They are formed by external forces such as river alluvial deposits and wave transport, and are widely distributed in rivers, beaches and desert areas.

Mining methods: mainly gravity separation methods are used, such as gold pans, jigs, и т. д..

6. Shallow low-temperature hydrothermal gold ore

Shallow low-temperature gold mines are mainly composed of minerals such as quartz, кальцит, и флуорит, and gold exists in the form of microparticles or fine particles. Formed in a shallow low-temperature hydrothermal environment, it is related to volcanic activity and magma intrusion. It is commonly found in the Pacific Rim volcanic belt, such as the western United States, Индонезия, Japan, и т. д..

Mining method: mainly cyanidation and flotation

7. Carbonaceous Gold Ore

Carbonaceous Gold Ore ore contains activated carbon or organic carbon, which adsorbs free gold and reduces the efficiency of cyanidation. The typical production area is the Homestake Gold Mine in the United States.

Ore dressing process: pretreatment (acid leaching or baking) + cyanidation gold extraction.

8. Gold-Silver Paragenesis Ore (Au-Ag Ore)

In Au-Ag Ore, gold and silver coexist in the form of solid solution or sulfide (such as argentite, native silver), such as the Taxco Silver Gold Mine in Mexico.
Treatment process: cyanidation or thiourea (silver can be recovered as a by-product).

9. Altered rock type gold ore

The gold content of altered rock type gold ore is as high as 600 g/ton, which is the “rich man” among gold ores and is formed in the process of magmatic activity and metamorphism.

Ore dressing method: After crushing and grinding, gold is separated by gravity separation, флотация, cyanidation and other methods.(need дробилка и grinding Mill)

10. Porphyry gold ore

Porphyry gold ore is mainly composed of minerals such as quartz, полевой шпат, слюда, и т. д.. Gold exists in the form of particles. It is characterized by the presence of copper minerals such as chalcopyrite, bornite or chalcocite, and gold minerals such as pyrite or native gold. It is formed in the process of magma intrusion and is related to magmatic hydrothermal activity. It is common in the circum-Pacific volcanic belt and some ancient orogenic belts.

Mining method: mainly using cyanidation and flotation.

Ссылка: Wikipedia Gold Mining

11 gold refining methods for gold ore

1. Sodium hydride alkaline solvent extraction method

Put the gold ore in a container, then add sodium chloride solution to completely dissolve the gold ore. Следующий, precipitate the gold ore in the solution, then put the precipitate
in a beaker, add copper sulfate solution to precipitate the gold in the gold ore. Окончательно, put the precipitate in a beaker, add silver nitrate solution to precipitate the gold in the gold ore, and you can get pure gold.

2. Gravity separation method

The principle of gravity gold ore separation is to use the high density of gold (19.3 g/cm³) and the density difference of gangue minerals to separate gold particles suitable for monomer dissociation (such as quartz vein gold ore) through gravity field.
Gold particles of different thicknesses can be obtained through different equipment.

3. Gold ore flotation method

The flotation method is to selectively adsorb gold particles through surfactants (collectors such as xanthate), and use bubbles to bring them to the surface of the slurry to form a foam layer. Grind the gold ore until the monomer is dissociated (200 mesh accounts for more than 80%), add collectors (such as butyl xanthate) and foaming agents (такие как сосновое масло). The gold content of flotation concentrate can reach 10-30 G/T., and subsequent smelting (such as roasting-cyanide gold extraction) is required. This method can process complex polymetallic ores (such as gold-copper paragenetic ores).

4. Magnetic separation method

The principle of magnetic separation is to use the symbiotic relationship between magnetic minerals (such as magnetite and ilmenite) and gold to separate them through a magnetic field. It is necessary to use a magnetic separator (weak or strong magnetic, magnetic field strength 500-15000 Oe) to select ores with close coexistence of gold and magnetic minerals (such as some quartz vein oxide ores).

5. Electrostatic separation method for gold ore selection

Electrostatic Separation is based on the difference in conductivity between gold and gangue minerals (gold has excellent conductivity) and is separated in a high-voltage electric field. The minerals enter the electric field after being charged by friction, and the gold particles are attracted to the negative plate, which is suitable for coarse particles of gold (>0.5 мм).

6. Cyanide separation method

Use cyanide solution to extract gold, which is suitable for low-grade ores. The principle is to use dilute sodium cyanide (NaCN) solution to dissolve gold and generate soluble gold-cyanide complexes:

4Au+8CN−+O2​+2ЧАС2​O→4Au(CN)2−​+4OH− .

Suitable for high grade concentrates.

7. Thiourea method

The principle of Thiourea Leaching is that thiourea (H₂NCSNH₂) forms a soluble complex with gold under acidic conditions:

Au+2SC(NH2​)2​+ЧАС+→Au(SCN2​ЧАС4​)2+​+ЧАС2​↑

Applicable to difficult-to-treat gold ores containing copper, arsenic and other sulfide ores.

8. Ferrocyanide method

The principle of Iron Cyanide Leaching for separating gold ores is to use potassium ferrocyanide (K₃[Fe(CN)₆]) to replace sodium cyanide to react and generate gold ferrocyanide:

Applicable to ores containing more carbonaceous or clay minerals (strong anti-interference).

9. Ion Exchange method

Ion Exchange uses resin to adsorb gold cyanide complexes (такой как [Au(CN)₂]⁻) in the solution, and then recovers gold through a desorbent (such as hot sodium hydroxide + sodium cyanide).
В этом процессе, the resin selectively adsorbs the gold complex (the adsorption capacity can reach 10-50 kg Au/t resin), and after desorption in a high-temperature alkaline solution, pure gold (purity> 99.9%) is electrolytically deposited. It is often combined with the carbon-in-place process (CIP/CIL) for large gold mines.

10. Bioextraction method

The principle of bioextraction of golden oreos is to use microorganisms to separate gold from ore. Первый, the ore is crushed, then microorganisms are added for fermentation, and finally the fermented solution is filtered to obtain gold. Bioextraction of golden oreos is widely used in gold mining and smelting industries, especially in the treatment of low-grade gold ores.

11. Combined extraction method

The principle of combined extraction method is to use multiple chemical substances to act at the same time to improve the extraction efficiency, and can extract multiple metals at the same time to improve resource utilization. The combined extraction method is widely used in the extraction of metal ores such as gold, медь, Ведущий и цинк, but the oreo golden combined extraction method requires precise control of chemical reaction conditions to prevent the loss of metal ions.

How is gold ore mined?

How to extract gold from gold mines? The quenching and extraction of gold ore is a complex process, which requires the selection of appropriate methods according to the type of gold ore, and also requires professional equipment to cooperate.

Так, do you know what are the processes and equipment for extracting gold from gold ore?