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Gold Ore Flotation Technology: Unlocking the Efficient Extraction Code for Gold Resources
2025-07-25 Xinhai (16)
2025-07-25 Xinhai (16)
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In the modern industrial system, gold is not only a favorite in the jewelry industry due to its brilliant luster and stable chemical properties, but also plays an irreplaceable key role in high - tech fields such as electronics, aerospace, and medicine. It is a well - deserved important strategic resource. With the increasing scarcity of high - grade gold ore resources globally, the efficient development of medium and low - grade gold ore resources has become the core task to ensure the sustainable development of the gold industry. Gold ore flotation technology, as a key means in the current gold ore beneficiation field, is constantly promoting the improvement of gold extraction efficiency and quality, opening a new chapter in the development of gold resources.
The core of gold ore flotation technology lies in skillfully using the differences in the physical and chemical properties of the surfaces of gold minerals and gangue minerals to achieve efficient separation. In the natural state, gold minerals, especially native gold, often show hydrophobicity due to the pollution of organic matter on their surfaces, and this characteristic is precisely the basis for flotation separation. When the ore is crushed, ground, and made into a slurry, specific flotation reagents such as collectors, frothers, and regulators are added. They will play their unique roles in the slurry. The collector can selectively adsorb on the surface of gold minerals, enhancing their hydrophobicity; the frother promotes the generation of a large number of stable bubbles in the slurry; the regulator is used to adjust the pH value of the slurry and the surface properties of other minerals, creating the best conditions for the flotation of gold minerals. Under the agitation and aeration of the flotation machine, the hydrophobic gold mineral particles adhere to the bubbles, float to the surface of the slurry with the bubbles, form a foam layer, and are then scraped and collected to achieve separation from the gangue minerals.
Xanthate is the most commonly used collector in gold ore flotation. Its molecular structure contains a polar group and a non - polar group. The polar group can chemically or physically adsorb on the surface of gold minerals, and the non - polar group makes the surface of gold minerals more hydrophobic, making it easier to adhere to bubbles. To further improve the gold recovery rate, xanthate is often used in combination with other collectors (such as promoters). In addition, agents such as alkoxy or phenoxyalkyl thiocarbamate, thiourea, dialkyl or diaryl monothiophosphate and monothiophosphonate, imidazole and aminothiophene can significantly improve the flotation selectivity of gold in pyrite - bearing gold; monothiophosphorous acid can selectively float gold from alkali metal sulfide ores, providing diverse options for the efficient collection of different types of gold ores.
In the flotation of gold, activators are mostly soluble alkali metal salts. Their metal ions can adsorb on the surface of minerals, changing the charge distribution and chemical composition of the mineral surface, expanding the floatable range of minerals, accelerating the floating speed, and improving the selectivity of flotation. Taking the flotation of gold - bearing pyrite as an example, copper sulfate is a widely used activator. Although its mechanism of action has not been fully clarified, research shows that when copper sulfate is used as a flotation regulator, the grade and recovery rate of gold, calaverite, stibnite - gold ore, pyrite, pyrrhotite, and arsenopyrite can be effectively improved. However, the adsorption amount of copper ions on the surface of pyrite is affected by the pH value of the slurry, and the adsorption amount is small in alkaline slurry. In addition, for the activation of stibnite, lead sulfate and lead nitrate often have better effects than copper sulfate.
Frothers play a crucial role in gold ore flotation. Their molecular structure has a hydrophilic end and a hydrophobic end. In the slurry, the hydrophobic end of the frother adsorbs on the surface of the bubbles, and the hydrophilic end extends into the water, forming a protective film with certain strength and elasticity, enabling the bubbles to exist stably and carry gold mineral particles to float. When separating monomer gold, the length and stability of the frother are particularly critical. Most gold ore dressing plants tend to mix polyethylene glycol ether frothers with other frothers to achieve the best results. When treating copper - gold ores (whose concentrates are usually sold to smelters) and having high requirements for flotation selectivity, weaker frothers such as MIBC are often selected to avoid excessive floating of other impurities.
For gold - bearing ores with good floatability of sulfide minerals, the single flotation process is widely used. After the raw ore is crushed and ground, it directly enters the flotation operation. By adding appropriate flotation reagents, gold minerals and sulfide minerals float out together to achieve the preliminary enrichment of gold. This process is simple and efficient, and can effectively enrich gold into sulfide mineral concentrates. Subsequently, gold can be extracted from the concentrates through further smelting processes, while achieving the comprehensive utilization of multiple metals.
When treating gold - bearing oxidized ores or ores associated with free gold, the gravity - flotation combined process has significant advantages. First, the gravity separation method is used to recover the coarse - grained gold in the ore. Gravity separation is based on the density difference between gold and gangue minerals, and the gold particles are separated by gravitational force. The tailings after recovering the coarse - grained gold then enter the flotation operation. Flotation can further recover fine - grained gold and other minerals closely associated with gold, thereby improving the overall gold recovery rate. This combined process gives full play to the respective advantages of gravity separation and flotation, achieving the effective recovery of gold minerals of different particle sizes.
The flotation - cyanidation combined process is often used for the in - depth treatment of gold concentrates. In the gold concentrate obtained by flotation, gold is still closely combined with other minerals. Through the cyanidation leaching process, gold is dissolved into the solution by cyanide. Subsequently, a reducing agent such as zinc powder is used for displacement, causing gold to precipitate from the solution to form gold mud. Finally, high - purity gold is obtained through processes such as pyrometallurgy. This combined process can significantly improve the gold extraction rate and is one of the important means to treat complex gold ores and obtain high - purity gold at present.
In the field of gold ore flotation, the large - scale and diversification of flotation machines are remarkable development trends. In the early stage, the large - scale of flotation machines was once limited in gold mines. However, in recent years, with the continuous progress of technology, some large and medium - sized concentrators have successively installed flotation machines with a volume of 4m³ and above, such as the BS - K4 type flotation machine. Practice has proved that this type of flotation machine is superior to the traditional XJK type flotation machine in separation indicators, saves nearly 50% of energy consumption, and also has many advantages such as strong adaptability, stable operation, and saving plant area. In addition, the internal structure and working principle of flotation machines are also continuously innovating. For example, the FloatForce® stirring mechanism equipped in the Metso TankCell® series flotation machine adopts the latest generation of stator - rotor technology. Through the separation design of the slurry channel and the air hole channel, a good stirring effect is achieved at a lower rotation speed. Its chimney - bottom structure changes the flow direction of the slurry in the tank, improves the suspension and flow characteristics of the slurry, effectively reduces energy consumption and the risk of tank sinking, and promotes the full mixing of the slurry and reagents, creating more favorable conditions for the flotation reaction.
As an efficient flotation device, the flotation column has once again become a research and application hotspot in the field of gold ore flotation after a long period of development and improvement. From the 1960s to the 1990s, developed countries have achieved fruitful results in the research of flotation columns. There are more than 100 related patents, and flotation columns suitable for various ore properties, different particle sizes, and different operation requirements have been successfully developed and successfully applied in foreign gold mines. The flotation column has the advantages of simple structure, small floor area, high separation efficiency, and low energy consumption. Its working principle is to use the counter - current movement of the slurry in the column body to make the bubbles and ore particles fully contact and achieve the flotation separation of minerals. Although there are relatively few reports on the application of flotation columns in domestic gold mines at present, with the continuous promotion and progress of technology, flotation columns are expected to play a greater role in the field of gold ore flotation in China.
Flash flotation machines are specially designed to deal with low - grade, fine - grained, and easy - to - slime refractory gold ores, and have become an innovation highlight of gold ore flotation equipment in recent years. Taking the Metso SkimAir® flash flotation machine as an example, it is installed in the underflow circuit of
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