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How to extract gold from sand? Differ from rock gold separation method, it is relatively simple to extract gold from sand. There are many simple methods, like panning, using a rocker box, using a sluice box, amalgamation and etc.. But it is proved that gravity separation method is the most effective and economic method through lots of practice.
Because the particle size composition of gold in sand and the particle size limits of different gravity separation equipment are different, the reasonable gold sand separation process should use the joint operation of several gravity separation machines. What specific methods are they? Let’s drive in now.
Shaking table concentrating
Unlike rock gold mines, gold sand can be directly washed without crushing and grinding. The purpose of the washing operation is to separate the sand from granular soil, and to clean the fine mud adhering to the gravel and mix the gold particles in it. The commonly used washing machine is spiral classifier. Then the washed sand is fed into screen for further process.
Generally, there is no gold contained in large gravel. In order to improve the efficiency of gold separation equipment, it is necessary to screen the gold sand after washing to remove large pieces of gangue mineral. Vibrating screens and trommel screens are widely used.
Next is the separating process, which applies jig roughing and shaking table concentration to remove most of the gangue mineral to obtain gold concentrate. Jig is used to process coarse particle, the particle size is bigger than 3mm, while shaking table is used to process fine particle, the particle size that can be recovered is 0.22-2mm.
Gravity separation is the key operation of placer gold beneficiation, so the effect of this process directly affects the beneficiation index of the entire placer gold beneficiation process.
After the combined process of jig and shaking table separation, the tailing slurry can be dewatered by filter press or thickener.
The above process is generally used in small-scale, high-grade gold sand concentrators. Because the capacity of jig and shaking table is small.
Spiral chute roughing
Shaking table concentration
After washing and screening with vibrating screen or trommel screen, the combined process of spiral chute roughing-jig scavenging -shaking table concentration is used to extract gold from sand.
The spiral chute is used to process ore with a particle size of 6-200 mm. The width of the chute depends on the throughput. Generally, it is 0.9-1.8 meters. The groove depth is 0.75 ~ 0.9 meters, and the length is usually not less than 5 meters.
And the coarse concentrate obtained from chute roughing is fed to jig for scavenging. The grade of coarse concentrate can be improved through this process, and the tailing loss rate can be reduced.
The shaking table is one of the main gravity separation equipment for fine-grained ore (0.22-2mm). In gold sand gravity separation, when roughing with a chute or jig, the coarse concentrate is usually enriched by a shaker with a very high ore ratio, its recovery rate can reach more than 98%, and directly get the final concentrate and abandoned tailings.
The above process is generally used in small-scale, low-grade gold sand concentrators. Because spiral chute is widely used for low grade ore.
3. Centrifugal concentrator concentration
Centrifugal concentrator concentration
After screening with trommel screen, the centrifuge concentrator is commonly used for in large-scale gravity separation plant. Because centrifuge concentrator has a larger capacity compared with other gravity machines like shaking table, jig and etc..
The main advantages of the centrifugal concentrator are large processing capacity, low recovery particle size lower limit, stable operation and easy operation. But its enrichment ratio is lower than shaking table.
After the centrifugal concentrator concentration, the tailing slurry can be dewatered by filter press or thickener.
You should already know how to extract gold from sand. However, in actual production, not all the placer gold mines use the same beneficiation process to obtain the best washing effect, so you should comprehensively consider the nature, characteristics and production scale of gold sand to apply the most suitable process and equipment. It is recommended to choose a professional manufacturer and let the professional engineer equip your plant with suitable beneficiation process and equipment.