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Gravity separation is one of the common methods for gold extraction. We have talked jigging separation and shaking table dressing before. Today we will introduce the other methods used for gold extraction, chute ore dressing, heavy media separation and hydraulic or pneumatic separation.
Chute ore dressing belongs to bevel flow separation process. The ore slurry is given to a certain inclined chute or inclined surface. Under the impulse of water flow, the ore particle group is loosely layered, the upper fine minerals are quickly discharged out of the tank, and the lower heavy ores are retained in the tank or discharged from the lower part at a low speed.
The chute is an intermittent operation. When the concentration deposit at the bottom of the chute reaches the moving degree, it is necessary to stop feeding the ore and clear the concentrate before the operation.
Chute ore dressing is suitable for processing small fine materials with low mud content, and the particle size of ore is 0.6 ~ 0.03mm. This process has the characteristics of simple structure, large processing capacity and low comprehensive cost. The spiral chute is the main gravity separation machine for gold extraction.
Heavy media separation is a gravity separation process that crush ores into a certain size, and make the density of the fluid heavier than water (that is heavy medium). According to the Archimedes' principle of buoyancy, when density is less than media, ore particles will float; when the density is greater than media, ore particles will sink. So we use this principle to process ore by adding media, to achieave the separation effect.
Heavy media separation processes include ore preparation, media preparation, ore sorting, media extraction, and media regeneration. This separation method is influenced by the density of mineral particles, and the particle size and shape of mineral particles. So the separation density can be accurately controlled, which can effectively separate minerals with small density difference.
When the broken materials settle in the air or water, the particles of different particle size and shape have different settling speed due to the different resistance of the medium they are subjected to. At this time, they can be separated according to the particle size. This kind of reselection operation is called classification.
Hydraulic classification is a gravity separation process in which a wide class of particles is divided into two or more narrow classes according to the different sedimentation rates of ore particles in water. In the process of hydraulic classification, water medium has three kinds of motion: vertical, nearly horizontal and rotary motion.
Due to the relatively complex process and low efficiency of wind power mineral processing, the application of pneumatic separation has a great limitation. It mainly used for dry closed circuit grinding, fine particle classification before dry separation, dry dust collection, etc.. Given to the small density of air media, the separation effect is not high. The selected particle size is generally 1.5-0.005mm, and the strength of individual fibers and sheets can be larger.
These are five common gravity separation methods for gold extraction. In production practice, method is favored by concentrators because of its advantages such as low production cost, simple equipment structure, less pollution to the environment and suitable conditions.
But which methods are better for us depends on the nature of gold mine. We can obtain a more ideal choice for gold extraction by beneficiation test.