When gold-bearing geological bodies are exposed to the surface, under the action of atmospheric, biological, water and other natural factors, they are weathered and broken to form gold particles and gold chips. Under natural transport, the densest particles gather on hillsides, riverbeds, lakes and seashores. When the gold in the sediment reaches the development and utilization standard, it becomes a gold deposit. Placer gold deposits can be divided into residual placer gold deposits, peregrine placer gold deposits, alluvial placer gold deposits, riverbed alluvial placer gold deposits and coastal placer gold deposits according to their depositional locations.
Usually, the placer gold beneficiation equipment mostly adopts centrifugal concentrator as roughing equipment. When the processing volume is large, it can be concentrated with a fixture before the centrifuge to reduce the amount of the centrifuge. Shakers have been used as cleaning equipment for centrifugal concentrates. The traditional way of the lock box can be used for the tailings of the centrifuge, and can also be used directly for the output of the screening.
01. Centrifugal Concentrator
The water-jacketed centrifugal concentrator uses the high-speed rotation of the inner cone of the centrifuge to drive the ore to rotate, so that the ore obtains a centrifugal force equivalent to dozens of times of gravity during the centrifugal rotation process. At this time, the difference in specific gravity of minerals is magnified by dozens of times. Due to the strong centrifugal force, the fine gold will not float on the water surface at this time, but will rotate at the bottom of the sorting tank through centrifugal force. At this time, high-pressure backwash water is used to prevent mineral compaction, and high-pressure water is used to push the sand with relatively low specific gravity out of the centrifuge's sorting tank. To achieve good beneficiation effect on fine gold.
It has been proved by experiments that centrifugal concentrators are indeed beneficial to gold. The recovery rate of gold above 100 mesh can reach more than 95%, which solves the problem of fine gold particles.
The main equipment for gold jigging is a jig machine, which mixes mineral particles of different specific gravity in a vertically moving variable-speed medium flow and stratifies them according to specific gravity. Minerals with low specific gravity are located in the upper layer, and minerals with higher specific gravity are located in the lower layer for reuse. The action of machinery and water flow separates the separated materials.
Jig beneficiation is a deep groove separation operation. It uses water as the beneficiation medium, and uses the difference in the specific gravity of the selected minerals to the gangue to carry out separation. The jig is mostly diaphragm type, and the stroke and the number of strokes are based on the specific gravity of the selected minerals. Can be adjusted flexibly.
The shaker separation method is the most widely used separation method in the separation of fine-grained materials. Because the flow layer of the separation medium on the bed is very thin, the shaking table belongs to the equipment of flow film beneficiation. It was developed from the early fixed and movable chutes, and later became a self-contained system characterized by its asymmetrical reciprocating motion.
The shaking table is a common equipment for sorting fine-grained ores. When processing metal ores, the effective sorting size range is 3~0.019mm. The outstanding advantage of the shaker is the high sorting accuracy, high-grade concentrate or waste tailings can be obtained after one sorting, and multiple products can be picked up at the same time.
04. Sluice box
The gold selection launder is a device that uses inclined water flow for separation. The material utilizes the combined force of water flow, mineral gravity and the friction between the ore particles and the bottom of the tank, so that the ore particles settle in different areas of the tank according to their specific gravity, and the specific gravity is small. The ore particles are taken away by the water flow, leaving behind the ore particles with a larger specific gravity, that is, the separation is completed.
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