Affect the separation accuracy of the heavy medium cyclone
Writer： admin Time：2020-08-21 10:31 Browse：℃
What are the factors that affect the sorting accuracy of the heavy medium cyclone? Let's understand together with the cyclone manufacturer: the factors that affect the separation accuracy of the heavy medium cyclone can be divided into two categories: one is the factors that are not easy to change in the production determined by the actual process conditions and the separation equipment itself , Such as the characteristics of the feed coal quality, the shape and diameter of the inlet of the cyclone and other structural parameters; the second is the factors that can be adjusted to a certain extent, such as the inlet pressure, the amount of slurry, and the method of feeding.
1. Feeding coal quality characteristics
heavy medium cyclone is a closed, relatively small sorting vessel. For a two-product cyclone, there is one inlet and two outlets, and the instantaneous volume flow of its entering and exiting are equal. The distribution of the displacement of the underflow port and the overflow port is basically fixed under certain conditions, but when the density composition of the selected raw coal changes, for example, the content of high-density matter increases, the discharge of underflow solids is required to increase, and the overflow solids The discharge volume is relatively reduced, but the discharge capacity of the underflow port is limited, so a part of the medium-density coal particles and heavy medium will be squeezed out to the overflow port to increase the actual separation density. Therefore, the change of the density composition of the selected raw coal will cause the fluctuation of the cyclone sorting density, which will definitely reduce the overall sorting efficiency.
2, the structural parameters of the cyclone
The selection of the diameter of the heavy-medium Hydrocyclone should meet the requirements of the processing capacity, corresponding to a certain minimum slurry volume throughput, and should meet the requirements of the centrifugal force of the separation, so that the heavy products to be separated are discharged from the underflow port. It is worth noting that although choosing a larger diameter cyclone can improve the separation efficiency, it may cause waste. The height of the cylindrical section of the cyclone increases, and the total volume and total length of the cyclone are increased, which is beneficial to sorting within a certain range. Too short will increase the probability of short-circuiting and overflowing of the feed material, and affect the quality of light products. The diameter of the underflow port is related to the proportion of heavy products (bang stone or medium coal) in the feed. Increase the underflow port. Under the same conditions, the actual separation density will be reduced, and the yield of clean coal will decrease accordingly. The reduction of the underflow opening will increase the actual sorting density accordingly. The diameter of the overflow port is usually proportional to the diameter of the underflow port. When other conditions remain unchanged, the reduction in the diameter of the overflow port will reduce the actual sorting density, causing some light particles that should have entered the overflow to be discharged from the underflow port. The form and diameter of the inlet have an important influence on the sorting. At present, most heavy medium cyclones use spiral or involute inlets, and the size of the inlet is increased. If the processing capacity of the cyclone (especially the discharge capacity of heavy products) is exceeded, the sorting efficiency will be lost; The size reduction will reduce the upper limit of the feed size.
3. Stability of heavy medium suspension
Maintaining the quality and stability of the heavy medium suspension is very important to the normal operation of the heavy medium separation system. The concentration of the resuspension liquid in the cyclone has a great influence on the separation efficiency, and excessive concentration will occur when the magnetite powder has a coarse particle size. In order to maintain a good sorting, the concentration of the medium is as small as possible. In actual production, in addition to avoiding the use of too coarse magnetite powder and keeping a certain amount of slime in the circulating medium, sometimes a small amount of clay or some natural or synthetic stabilizers can be added to the medium in the past.
4, the amount of circulating medium
The volume of the heavy medium cyclone is very small, and the residence time of the heavy medium and coal in it is basically the same, only a few seconds. In order to ensure the necessary liquid-to-solid ratio for effective separation, the circulating medium volume of the heavy medium cyclone is relatively large. For raw coal of different particle sizes and densities, the amount of circulating medium is generally 3 to 5 times per ton of raw coal. For a three-product heavy medium cyclone, the amount of circulating medium may sometimes exceed this upper limit. The separation efficiency of the heavy medium cyclone is greatly affected by the liquid-solid ratio.
5, the inlet pressure of the heavy medium
In principle, the inlet pressure of the heavy medium should cause enough centrifugal force to be generated in the cyclone so that heavy particles with a density higher than the sorting density can enter the underflow. Increasing the inlet pressure will increase the centrifugal force generated in the cyclone and increase the recovery rate of fine-grained heavy products in the underflow, but it will also enhance the concentration of the suspension in the cyclone. At the same time, due to the increase in inlet pressure, the slurry throughput of the cyclone increases, thereby reducing the residence time of slurry in the cyclone, increasing the overflow discharge, and leading to a slight increase in the actual separation density.
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