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Gold ore beneficiation- Gravity separation method

2022-02-14 Xinhai (250)

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Gravity separation is a process of obtaining products with different densities or different particle sizes by using the difference in density and particle size of minerals, and by means of the combined action of medium fluid and various mechanical forces to create suitable loose stratification and separation conditions. Since most gold-bearing ores contain a certain amount of coarse-grained free gold (+0.1mm), it is difficult to recover by flotation and hydrometallurgy. Therefore, the gravity separation method is mostly used to separate the placer gold and vein gold before and after flotation and leaching to recover the coarse-grained gold that is dissociated from the monomer. Generally, the lower limit of the particle size of gold that can be recovered by the gravity separation method is 0.01 mm.

 Gravity beneficiation method of placer gold ore

1、Gold selection by jig


The main equipment for gold jigging is a jig machine, which will mix mineral particles of different specific gravity, and stratify according to specific gravity in a vertically moving variable-speed medium flow. The action of machinery and water flow will discharge the layered materials separately. Jigging gold is suitable for sorting coarse mineral particles (mineral raw materials of any particle size except fine materials), and the benefit particle size range of its metal minerals is 0.074-50mm. Under the premise of dissociation, the lower limit particle size can reach 0.04mm, the process operation is simple, the equipment processing capacity is large, and the application effect is very good in roughing gold ore.

2. Gold Shaking Tables Selection


The main equipment for the gold separation of the shaking table is the Concentrating Table (Shaking Table), which is the equipment for separation in the horizontal medium flow. The transmission mechanism is used to drive the bed surface to do longitudinal reciprocating motion, and the rush flow and the bed surface differential motion, and the ore particles are in the reciprocating motion. It undergoes the layering action perpendicular to the bed surface and the separation action parallel to the bed surface, so that materials of different particle sizes are discharged from different sections of the bed surface to realize sorting.

Shaking gold selection is suitable for processing and sorting minerals with fine particle size, and can be divided into three types: coarse sand bed, fine sand bed and ore mud bed according to the particle size of the ore. Among them, the coarse sand bed is suitable for sorting ore particles with a particle size of 0.5-2.0mm, the fine sand bed is suitable for processing ore particles with a material particle size range of 0.074-0.5mm, and the slime bed is suitable for processing materials with a particle size of 0.037-0.074 mm grains.

The ore feeding particle size range of shaking table gold dressing is generally between 0.019-3mm, the gold dressing is stable and reliable, the ore belt distribution is clearly visible, the rich ore is higher than other dressing methods, easy to manage, and the required ore can be sorted at one time.

3. Chute gold selection method

The main equipment for gold selection in chute is spiral chute, which is a kind of equipment that uses inclined water flow for sorting. The material is made of water flow, mineral gravity, friction between ore particles and the bottom of the tank and other combined forces, so that the ore particles settle in the tank according to their specific gravity. In different areas in the interior, the ore particles with a small specific gravity are taken away by the water flow, leaving behind the ore particles with a large specific gravity, that is, the separation is completed. The spiral chute is suitable for processing fine-grained materials with low mud content, and the material size range is 0.03-0.6mm.

Gravity beneficiation method of vein gold ore

In the pulse gold concentrator, the gravity separation method is rarely used alone, and is mostly used as a part of the combined gold separation process. Generally, in the grinding and grading circuit, a jig or a spiral chute is used in conjunction with a shaking table to recover the dissociated coarse-grained monomer gold in advance, so as to facilitate subsequent flotation or station operations, and obtain qualified of gold concentrate. This kind of gold beneficiation method is more commonly used in the mining hills of small gold mines.

1. Gravity-cyanidation combined process

This gold ore beneficiation process is suitable for the treatment of quartz vein gold-bearing oxide ore. The raw ore is re-separated first, and the concentrate obtained by gravity is subjected to validation to extract gold; or the raw ore is directly re-separated, and the tailings and graded ore are then cyanided separately.

2. Gravity-flotation combined process


This gold beneficiation process is to first use gravity separation to recover coarse-grained gold in the ore, and then gravity separation of tailings for flotation. The gold ore beneficiation process is suitable for treating ore treated by single flotation, gold-bearing oxidized ore and ore associated with free gold, and can obtain a higher recovery rate than single flotation process.

3. Flotation-gravity combined process

This gold ore beneficiation process is mainly based on flotation, which is suitable for ore with close symbiosis of gold and sulfide and can only be recovered by smelting method. It is also suitable for coarse accumulation and uneven distribution of gold-bearing quartz vein ore. Flotation can achieve higher recovery rates.

Taking the gravity beneficiation process of rock gold ore as an example, in the closed-circuit grinding system, the coarse-grained gold is easily enriched in the circulating material or embedded in the lining plate (or medium) of the mill, resulting in the loss of gold, and the gold particles have great toughness, not easy to grind in the grinding process. The cyanide leaching process is a diffusion-controlled process, and this part of the gold dissolves slowly, which is easy to cause incomplete leaching and thus remains in the cyanide tailings. Therefore, in the grinding process, the gravity separation method is mostly used to recover this part of the coarse gold in advance.

As for the Gold ore beneficiation, gold placer generally adopts gravity separation method to separate gold and heavy sand minerals; while for vein gold ore, combined beneficiation processes such as flotation, gravity separation and cyanide are used, and stage grinding, Separation process, implement the beneficiation principle that can be harvested early, and recover coarse-grained gold in time.

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