The third type of classification used in mining is the Hydrocyclone, commonly called a Cyclone. Unlike the others it has no moving parts and is worked in conjunction of another piece of equipment, a pump. To understand the Hydrocyclone Working Principle we must first know its components. Beginning at the top, there is the OVERFLOW DISCHARGE.
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This is simply a length of pipe, its purpose is to provide a point of separation between the coarse and fine material. A better explanation will be possible once we begin explaining how it works. Next in our list of cyclones components is the UPPER and LOWER CONE, not all hydrocyclones have this section divided into two cones. Some are designed this way do to make repairs easier, and to isolate wear points, Their function is to help create a VORTEX. The centre of this spiral is called the VORTEX. The purpose of the apex is to cause internal pressure for the cyclone and to create a vortex that extends all of the way to the top of the cyclone. In all hydrocyclones there are two outlets, one for the coarse material, this is the APEX, and the other for the fine material, which is the VORTEX FINDER. The purpose of the Vortex finder is to separate the fine material from the coarse as it spirals around the vortex. The WIDTH of the Vortex finder will determine how far into the coarser material the separation point will be. The Volume of slurry that is being fed into the cyclone must not exceed the capacity of these two outlets that allow it to escape. The size of the apex and the vortex finder is crucial. If the apex of the cyclone, like the size of the drain in your sink, is made smaller it wont allow as much slurry out of the underflow of the cyclone. This will cause the vortex to be smaller the internal volume of the slurry inside the cyclone will be greater and the amount of material that the vortex finder separates to become part of the overflow will be increased.
The size of the apex in relationship with the volume of slurry that is being fed to the cyclone, will create and maintain the PRESSURE NECESSARY to force the fine material out of the cyclone. The greater the pressure the greater the volume of overflow. To increase the overflow requires either a higher volume fed to the cyclone or a smaller underflow discharge opening. As the pressure in the cyclone climbs the amount of coarser material in the overflow increases. The reason that this pressure is generated is because the volume of the feed is greater than apex discharge capacity. The pressure is generated as the volume of slurry is built up over the apex.
These three factors then become your operating Variables when dealing with cyclones, APEX SIZE, the SIZE of the VORTEX FINDER, and the VOLUME of the feed. The CYCLONE PRESSURE becomes a control indicator for the adjustment of the apex size and the volume of the feed. The vortex finder is a FIXED VARIABLE, meaning that it can be changed to affect the sizing of the overflow, but not as a normal operating practice. The cyclone must be removed from service and taken apart to make that adjustment.
If the variables become unbalanced to the point where the pressure is too high, the cyclone will overload. What this means is that when a vortex is generated, an air column is formed in the center of the vortex. If this air column collapses, the velocity of the spiral will decrease far enough to lose the centrifugal force that causes the ore to classify. As the internal pressure of the cyclone represents the volume of slurry that is in the cyclone it only follows that the reason that the air column should collapse is that there isnt room left in the cyclone for the air.
If the variables become unbalanced in the opposite extreme then there wont be enough pressure to cause an overflow. Either the volume will be too low or the apex size too large. This will result in all of the feed being discharged out of the underflow.
By what you have just learned it is apparent that to maintain an even pressure on the cyclone is very important. If the cyclone is dependent on pressure to function effectively then a constant pressure would ensure positive control over the classification of the ore. This means the pump that feeds the hydrocyclone is very important to the effective working of that hydrocyclone.
Before feeding the slurry to the hydrocyclone, you can use a screen to separate the grass, sawdust and other debris to prevent the hydrocyclone from blocking. Generally, the slag removal screen mesh is about 1/6 1/5 of the grit port diameter. To Wrap Up. The above introduced 6 aspects to improve the efficiency of hydrocyclone.
The hydrocyclone ensures effective ore fineness and reduce middlings. It also can use the single tank to select Pb avoiding the over crushing, and improve the classification efficiency. Based on keeping the original lead and zinc recovery rate, hydrocyclone installation effectively improves the processing quantity 7.3%.
Ore Classifying And Separation Hydrocyclones Design For . Hydrocyclone has been extensively used for closed circuit grinding and classification system , thickening, desliming, dewatering , tailings filling, damming, recovery processes in ferrous, nonferrous metal and nonmetal mine industries, and is deeply popular with customers due to high classification efficiency, simple structure, large ...
2019 05 09 by JXSC Mining. Hydrocyclone is a grading device that uses centrifugal force to accelerate ore particle deposition. It needs the pressure to feed ore, so it consumes a lot of power but occupies a small area, cheap, the processing capacity is large, The classification efficiency is high, obtain very fine overflow product, mostly used in the second stage of closed circuit grinding classification equipment.