| China is a country with a huge demand for non-ferrous metal resources,it is particularly important to use and recycle metal resources rationally.Among them,aluminum and copper have high content and high economic benefit in waste nonferrous metals,so these two kinds of nonferrous metals are the focus of recycling industry.The separation of metal and non-metal,metal and metal can be realized only when the scrap non-ferrous metal is broken to a certain extent.The separation of small size(≤5 mm)metal is of great significance for the recovery of scrap non-ferrous metal.Based on vertical drum eddy current separator(VDECS)as the research object,this paper establishes the movement model of VDECS(including magnetic field distribution,eddy current force and movement model).Separation rules and mechanism are analyzed through the experiment of single and mixed particles between VDECS and horizontal drum eddy current separator(HDECS).Then,VDECS is analyzed and optimized.The main research contents and results are as follows:(1)Establishment of vertical drum eddy current separation movement model.By fitting the measured magnetic field data,the distribution formula of the radial magnetic field intensity on the surface of drum is obtained.According to Faraday’s law of electromagnetic induction and Bio-savar’s law,three formulas of eddy current force in different shapes are derived.In addition,particle shape has little effect on eddy current force when the volume is the same.Using the formula of eddy current force,a vertical drum eddy current separation movement model is proposed,which is consistent with the measured trajectory.(2)Comparative analysis of VDECS and HDECS.According to the range analysis of orthogonal experiment,the order of influence of each factor on the separation effect is as follows:VDECS is that particle size>rotation speed>feeding height>particle shape;HDECS is that particle shape>particle size>conveyor speed>rotation speed.In VDECS,the larger the rotation speed,the larger the particle deflection distance.However,when the rotation speed increases to a certain degree in the HDECS,the deflection distance becomes smaller because the particles jump ahead of time.In the VDECS,the deflection distance increases linearly with the increase of particle size,but in the HDECS,as the particle size increases,the eddy current force increases,causing the particle to jump ahead of time,and the deflection distance growth gradually slows down.For particles of the same size,the average deflection distance of VDECS is smaller than that of HDECS,but the distribution of particle drop points is more concentrated,which is more conducive to the separation between metals.Shape factors have little influence on the deflection distance of particles in VDECS,which is beneficial to the separation of the same material with different shapes.However,in HDECS,the deflection distance of cube particles is much larger than that of sphere and cylinder,which is related to the torque and eddy current force exerted by particles in the process of movement.Under the same parameters,the separation efficiency of aluminum and copper in VDECS is higher than that in HDECS.(3)Performance analysis of VDECS.The influence of size,uniformity and operating parameters(rotation speed and feeding height)on the separation effect is investigated by using probability density distribution method.The minimum size of VDECS is about 4 mm,with the increase of material uniformity,the better the separation effect.With the increase of rotation speed and the decrease of feeding height,the greater the difference between the probability density distribution of aluminum and copper,the higher the separation efficiency. |
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