Research On The Effect Rule About The Magnetic Field To The Separation Density In Dense Medium Cyclone

To solve the problem of adjusting the second cyclone separation density in the three-product dense medium cyclone, this thesis mainly research the effect of magnetic field on the distribution of dense medium in the cyclone. Cyclones with cone angle 20°and 45°were designed and produced with PMMA. Type Ⅰ and Ⅱ solenoid were made by man based on the solenoid theory calculation formula. Experiments are did through the combination of cyclone and solenoid in different exciter current and solenoid position, and the medium distribution rule in the cyclone influenced by magnetic field is put forward.In conditions of 20°cone angle cyclone and type Ⅰ solenoid combination, the distribution of dense medium in cyclone was researched for different factors such as solenoid position and magnetic field intensity. Representative test conditions were selected to do the -0.5mm coarse slime separation experiment, and test the ash content of -0.5+0.25 mm level slurry. The result indicates that, in cylinder segment of the cyclone, the magnetic field produced by exciter current in 0-1.5A range can improve the separation density, and ash content of both clean and tail coal were elevated, when continue to increase the exciter current, the dense medium cyclone cannot select effectively, which lead to low ash content of clean and tail coal, and also the clean coal production rate. The promotion of magnetic field to separation density is most significant at the position where the axis center of the solenoid is higher than the overflow orifice. In the cyclone cone segment, the separation density can be reduced as long as there is magnetic field, in this condition, the ash content and production rate of clean and content of tail coal ash are reduce, the reduction of separation density is larger with the increase of the magnetic field strength.In conditions of 20°cone angle cyclone and type Ⅰ solenoid combination, using the same experimental method as is taken in the former combination. It is observed that in cylinder segment of the cyclone, the magnetic field produced by exciter current in 0-6A range can improve the separation density. When the current continue increase to a certain value, invalid separation appears in the dense medium cyclone under the function of high-intensity magnetic field. And the promotion of magnetic field to separation density is most significant at the position where the axis center of the solenoid is higher than the overflow orifice. In the cyclone cone segment, the separation density reduce at a little magnet field, the reduction of separation density is larger with the increase of the magnetic field strength.In conditions of 20°cone angle cyclone and permanent magnet, the distribution of dense medium in cyclone was researched for different factors such as magnet position and magnetic field intensity. Representative test conditions were selected to do the -0.5mm coarse slime separation experiment, and test the ash content of -0.5+0.25 mm level slurry. The result indicates that the separation density can be reduced when one magnetite is put at the cone segment, but the underflow orifice would be blocked up when the number of magnet near the underflow orifice reach a certain amount. While the overflow medium ratio, overflow density and underflow density are reduced when the magnets are placed on the upper part of the cyclone tube especially the overflow, this shows that the separation density has decreased in the cyclone.The magnetite enrichment experiments are proceed at a low magnetite concentration with the combination of 45°one angle cyclone and I type solenoid. The results show that the higher the exciter current of the solenoid the better the magnetite concentration and the effect of the magnetite concentration has a little to with solenoid position.This thesis based on the laboratory experiments validates the conclusion verified by foreign scholars that the electromagnetic field can reduce the separating density. And it has been found that in a certain magnetic field positions and specific magnetic field intensity the separating density can be improved. This thesis refers to the preliminary conclusion that the magnetic field can regulate the dense medium cyclone separating density in two-way, the conclusion can be the foundation for the magnetic field industrial application in adjusting the second cyclone separation density in the three-product dense medium cyclone.