Electric selection equipment and process technology---electric classification equipment

The drum type electric sorter actually has a function of classifying according to the particle size. If there is no electric field, according to the centrifugal force and gravity of the ore particles on the drum surface, there will be a classification according to the particle size. The large size and density of the ore particles will be thrown to the farthest place in front of the drum, medium and secondary. The fine particles are closest to the drum. If the electric field is increased, a very important force is added to make the classification more effective.
(1) Drum type electric classifier
Figure 1 is a simplified diagram of the drum type electric sorter grading the same material with different precision and different materials.

As can be seen from the figure, material grading is the result of the combined action of various forces and can be expressed as follows:

Where F———combined force, N;
F _e ———Electricity, here is the mirror suction, N;
F _c ——— centrifugal force, N;
F _g ———Gravity, N;
F _r ———air resistance, N.
For the same type of non-conductor material, such as a composite electrode using a corona pole or a combination of a corona pole and a static electrode, as long as the charge adsorbed by the ore particles is small and the centrifugal force exceeds the electric power, the coarse particles must fall before the drum. , then its expression is:
F _c +F _g >>F _e +F _r
For medium-sized ore particles, the relationship is as follows, and falls between the coarse particles and the fine particles.
F _e +F _g >F _e +F _r (2)
For fine particles, it must fall behind the drum, and its expression is:
F _e +F _c >F _g +F _r (3)
Regardless of the classification of the material, fine particles are often easily mixed into the coarse fraction, while the coarse fraction is unlikely to be mixed into the fine grade due to the influence of the gas flow and the electrostatic field. [next]
(2) Chamber-type electric classifier This is based on the difference in electric power, gravity and air resistance received during the process of falling, so that the trajectory of the falling is different, so that the ore particles can be classified according to the particle size.

Fig. 2 is a schematic diagram of the chamber classifier, in which the material is fed into the space of the corona pole 2 and the grounding pole 3, where the electric charge is obtained. When a particle with a small particle size is charged, it is larger than the surface charge, and is subjected to a large electric field force, but the mass is small, and the gravity is small, so that it settles quickly on the grounding electrode 3; the larger granular particle is opposite. Therefore, the sediment is in the lower part, and the rest is between the fine and coarse grains. For example, according to the lateral position, the closer to the center position, the coarser the particle size, and the farther the particle size is, the finer the particle size is. According to the settlement height, the finer the upper particle size, the thicker the lowermost layer. Figure 3 is a chamber type industrial electric classifier.

In addition to the above-mentioned grading equipment , there is also a frictional adhesion grading apparatus which can classify materials having a small particle size (0.04 mm), the principle of which is the same as that of the above-mentioned drum type.