The hydrocyclone is a more effective fine-grain grading device currently in use.
The construction of the hydrocyclone is relatively simple, as shown in Figure 3-2, with a cylindrical portion at the upper end and a conical container underneath. The slurry is fed into the cyclone at a certain speed (generally 5 to 12 m/s) in a tangential direction, and a rotary motion is obtained, thereby generating a large centrifugal force (usually several times or even hundreds of times larger than gravity). Under the action of centrifugal force, the coarser particles are thrown to the wall of the vessel and move downwards along the trajectory of the spiral, which is discharged into a coarse-grained product by the grit nozzle; the finer particles and most of the water are traced by the inner spiral. The overflow pipe is discharged.
The cyclone is widely used to:
1 grading before de-sludge, concentration and fine-grained materials;
2 used as a classification device in the grinding system;
3 as a centrifugal heavy medium sorting device.
There are two factors that affect the operation of the hydrocyclone.
(1) Structural parameters of the cyclone
1 The diameter productivity and overflow particle size of the cyclone increase with the increase of its diameter. Usually, the large diameter cyclone is inefficient, and the overflow has a large amount of coarse particles.
2 The size and shape of the ore mouth is increased to the size of the mine mouth, the treatment volume is increased, the overflow particle size is coarsened, and the classification efficiency is decreased.
3 The diameter and insertion depth of the overflow pipe increase the size of the overflow pipe, the treatment volume increases, the overflow particle size becomes coarser, and the classification efficiency decreases.
4 The diameter of the sinking nozzle is large, the overflow is small, and the overflow granularity is fine. The sanding nozzle is small, the concentration of the sand is high, the overflow is large, and the coarse grain content is high.
5 column height The height of the column affects the length of time the slurry is subjected to centrifugal force. Generally, the height of the column is 0.6 to 1.0 times the diameter.
6 The cone angle of the cyclone mainly affects the separation granularity, the cone angle is large, and the coarse particles are easily mixed into the overflow; the cone angle is small, and the overflow particle size becomes fine.
(2) Operating parameters of the cyclone
1 The ore pressure mainly affects the treatment volume and graded particle size. Increase the ore pressure, the classification effect can be improved, and the concentration of grit is increased.
2 The concentration of feedstock feedstock and its particle size composition directly affect the concentration and particle size of the product. The finer the graded particle size, the lower the feed concentration should be.
3 overflow and grit discharge mode The best working state of the cyclone is that the grit is sprayed in an umbrella shape. The angle of the umbrella surface should not be too large, just to be able to spread out. When used for concentration, the grit is discharged at the highest concentration in ropes. When used for dewatering, the grit is discharged in the largest umbrella shape with the least amount of overflow.
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