Then we look at the process of manual gold selection. When adopting the re-election process, there seem to be two conditions, one is water and the other is vibration. Among them, water is used to disperse useful minerals and gangue, and vibration is to use gravity difference. Quickly separate and form stratification, how to achieve it in mechanical manufacturing? We interpret it through common gold re-election equipment.
Jig
The jig is a kind of re-election equipment with a wide range of feed sizes. At present, the jigs produced in China range from a maximum of 75mm to a minimum of 0.043mm. Of course, each jig has a suitable grain size. Scope, the maximum feed size of the jig is mainly related to the concentrate discharge. No matter what structure of the jig is indispensable for four systems, feeding, transmission, flushing, vibration, feeding system in order to ensure uniform feeding, so that the material through the equipment is basically the same time, for the tailings and concentrate indicators The control is also basically the same, the transmission system ensures the material transportation, realizes the continuity of operation, the bottom flushing, the material dispersion accelerates the separation speed, the vibration can avoid the crushing and ensure the stability of production.
In the gold beneficiation process, the use of the jig is usually the same as the traditional amalgamation method. Generally, it is in a section of grinding ore discharge, the feed size is less than 1mm, and the difference in specific gravity is used to obtain free gold. Of course, due to sulfide minerals. The specific gravity is also relatively large relative to the gangue, and will also be discharged at the bottom with the gold sand, so the quality of the jig concentrate is not very high, usually at 100-300g/t.
Nielsen re-election machine
The Nielsen re-election machine is composed of two concentric cylinders. The inner rotating cylinder uses the centrifugal force to stratify the material, and the outer rotating cylinder reverses the water supply, so that the material is loose, the separation speed is accelerated, and the separation efficiency is improved. Nielsen inner cylinder can generate 60 times gravity centrifugal force when running. Through external flushing, qualified products can settle against water flow. The gangue and relatively light minerals are screwed out of the inner cylinder to form tailings. Rotating speed, Nielsen re-election machine can obtain high-grade gold concentrate, usually up to 1000-3000g/t.
Strictly speaking, the feeding requirements of Nielsen re-election equipment are in the range of 0.3-1mm, which means that it is suitable to be placed in the sand returning outlet of the classifier. However, because a large amount of flushing will reduce the concentration of the slurry, it is not suitable for the feeding of the mill. In the field layout, it is often arranged in a section of ball mill overflow. Due to the influence of fine-grained materials on the index, the actual production of Nielsen gold concentrate is generally 500-1000g/t.
Shaker
The shaker is the most similar to the manual gold selection equipment. All the shakers are composed of the bed surface, the frame and the transmission system. For the granularity of the ore, the groove of the bed surface is different, and the bed surface is slightly inclined. The feed port and the water supply port are arranged on the high side, and the material enters the shaker. As the vibration is gradually dispersed throughout the bed surface, the water is washed away, the lighter minerals are more and more away from the feed side, and the heavy minerals are less laterally offset. Since the mining method is open, the capture of concentrate tailings is achieved by manual interception, and the concentration of ore, flushing and vibration frequency will affect the location of the ore discharge, so the experience of the operators is very demanding. strict.
Because the unit processing capacity of the shaker is very low, it is generally not used as the main equipment for gold beneficiation. At present, most of the plants using shakers are used as re-enrichment of tailings after flotation, and the ore content usually exceeds its production limit. Therefore, the concentrate index obtained will not be very high.
Blanket
When I saw the blanket for the first time, I was really surprised. I never thought that daily necessities could be used for gold beneficiation. Of course, the blanket is also a kind of re-election equipment. When the pulp passes through the blanket, the surface fluff is on the particles. The formation of obstacles, due to the relatively heavy gold (gold-containing minerals), quickly sinking under the interference and adhered to the blanket, the gangue is lighter and continues to be washed away by the water, thus achieving separation. Blanket selection does not require special equipment. A tank is built manually. It is about 800 meters wide, about 10 meters long, and 3-5% slope. It can be laid on the most common blanket. When more and more minerals are enriched, the carpet can be dried and burned to obtain concentrate.
Of course, the blanket itself is unpowered equipment, there is no external flushing for dispersion, no vibration to accelerate separation, so the sorting efficiency is very low, and the irregular surface of the particles will also affect the adhesion of the felt, so the blanket is also Can not be used as the mainstream equipment for gold selection, can only be recycled as tailings.
There are many equipments for gravity gold selection. Equipment manufacturers are constantly improving the technology. The purpose is to improve the enrichment ratio and improve the recovery rate. However, there is not much research on the process, and the famous domestic mineral processing experts, Changjiang Scholars, China. Professor Cao Yijun from the University of Mining and Technology proposed a pre-grinding tailing, which introduces a new idea to the traditional gold-plating process. It proposes to pre-cast the broken products before the grinding process in order to expand the current low-grade gold mine. Processing capacity, reduce production unit consumption, through the test, will feed about 1.7g / t ore, through the tail to obtain 2.5g / t product, the tailing rate of about 30%. Laboratory tests have been completed and will soon enter the semi-industrial trial.
Whether it is re-election or flotation, the effect of fine-grained grade is always a big disturbance of the beneficiation index. In general, the sorting index of -500 mesh (-0.029mm) is much lower than -200 mesh. This is also an important reason why it is difficult to obtain high recovery rate of fine-grained gold mines. The high-speed disc sorting machine developed by Maid Group is used for gravity separation of 5-29 micron size. In China National Gold Group Zhongyuan Mining Co., Ltd. The company has made major breakthroughs in demineralization of oxidized ore. At present, we are constantly trying to sort minerals. Whether it is possible to achieve breakthrough results in difficult gold mines in the future, we will wait and see.
For gold, the best " collector " is cyanide. The reason why we put cyanidation in the back is because of its high cost, of course, as one of the most effective methods of gold selection.
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