Effect Of Rotating Magnetic Field On The Transport Characteristics Of Dense Medium In Cyclone And Its Separation Effects

In order to realize the idea of on-line control of the separation density of the dense medium cyclone.Drawing lessons from the application of the rotating magnetic field in magnetic grinding,the motion control of magnetic targeted drug carriers and the change of the static magnetic field on the sorting density of the dense medium cyclone,it is proposed to apply it at the position of the upper end cap and the cylinder body of the dense medium cyclone.The coaxial rotating magnetic field accelerates the magnetic dense medium in the cyclone,and controls the movement of the magnetic heavy medium in the cyclone by controlling the rotation speed of the magnetic field,thereby realizing the idea.In order to explore the influence of the rotating magnetic field on the movement of magnetic particles,a rectangular permanent magnet made of neodymium iron boron is used to construct a 6-pole circular magnetic field with alternating NS and full NN arrangements.Permanent magnets placed horizontally and vertically are used to simulate the swirling current.The rotating magnetic field at the position of the end cover and the cylinder body is controlled by changing the number of permanent magnets to control the magnetic field strength;the frequency conversion motor is used to drive it to rotate,and the frequency converter is used to control the magnetic field speed.To facilitate observation,different numbers and diameters of steel balls and 201 stainless steel rods are used to simulate magnetite powder particles.The high-speed camera system was used to observe the movement patterns of steel balls,thin rods,dry and wet magnetite powders under different magnetic field characteristics.The magnetite powder suspension of different concentrations was mechanically stirred,and the level change under the action of the rotating magnetic field was observed;and the coarse slime sorting experiment was carried out on the basis of the above research and observation.The results show that the acceleration of magnetite suspension caused by N-S or N-N rotating magnetic field is caused by the reversal of magnetic chain.In contrast,under the rotating magnetic field of N-S arrangement,the reversal angle of the magnetic chain is larger and the reversal process is more continuous,so the acceleration of magnetite powder suspension is more obvious.However,with the increase of the rotating speed of the rotating magnetic field,the phenomenon of layered aggregation of magnetite powder appears,and the "ring like" magnetic ring is formed,which is easier to appear in the N-S arrangement of the rotating magnetic field.It is found that the more magnetite powder is,the higher the magnetic field intensity is,and the lower the magnetic field speed is when stratification occurs.Combined with the motion state of the steel ball group in the rotating magnetic field,the relevant motion model is established,and it is pointed out that this phenomenon is gradually formed by the mutual attraction and accumulation of magnetic chains with different magnetic poles,and the magnetic rings are independent of each other.The reversal direction of the flux linkage is opposite to the rotation speed of the magnetic field except in the low-speed rotating magnetic field with N-N arrangement.When the magnetic field is stationary,it will hinder the rotation of magnetite powder suspension.Based on the above shooting test,the coarse slime separation test of dense medium cyclone was carried out.The cyclone separation test shows that the static magnetic field will destroy the separation effects of the cyclone,and the rotating magnetic field in the same direction at the end cover will only reduce the overflow ash of +1 mm size fraction.The rotating magnetic field opposite to the feeding direction will significantly reduce the ash of +0.25 mm size fraction in the overflow and the separation density of these size fractions.The coaxial rotating magnetic field located in the cyclone cylinder reduces the separation density of +0.5 mm size fraction,but destroys the separation of-0.5 mm size fraction.The reverse rotating magnetic field reduces the separation density and improves the separation accuracy.The result of separation test is consistent with that of camera,which confirms the acceleration effect of reverse rotating magnetic field on magnetite powder.This phenomenon has a certain guiding role for the development of new magnetic separation equipment.