Optimization Of Magnetic Field Distribution Of Magnetic Separator And Influence Of Shape Of Sorting Chamber On Flow Field Distribution In Sorting Area

At present,China is in the primary stage of socialism in which industrialization and urbanization are rapidly advancing and consumes a large amount of iron ore resources.In addition,due to the characteristics of “poor,fine,miscellaneous,scattered” of iron ore resources in China,and the Inner Mongolia Autonomous Region is in arid and drought-stricken areas.Although the wet magnetic separator is widely used in the iron ore mining industry,and the obtained iron fine powder has a higher grade,it consumes more water,consumes more energy,and is easily clogged.Therefore,from the perspective of sustainable development,the dry magnetic separation does not require water resources,the processing capacity is large,the operation is convenient,and the adaptability to the ore size and the ore grade determines that the dry magnetic separation is more suitable for the separation of iron ore in the autonomous region..In this paper,the magnetic field characteristics of the magnetic system of the magnetic separator and the flow field characteristics of the gas-solid two-phase flow in the sorting chamber are studied from theoretical analysis and simulation.Firstly,in order to optimize the magnetic field distribution,the magnetic field current-free module of the simulation software COMSOL Multiphysics is used to simulate the magnetic induction,circumferential magnetic field strength and radial average magnetic field gradient of the magnetic system formed by different magnetic block structures,and monitors the outer surface of the magnetic system with a magnetic circular particle having a diameter of 2 mm by using a probe.It draws the following conclusions: the magnetic system added to the auxiliary magnetic block has more uniform fluctuation of the magnetic field strength curve at the magnetic pole center line and the magnetic pole gap,and the circumferential magnetic field distribution is more uniform,which is more favorable for the magnetic particles captured by the magnetic roller to uniformly move along the magnetic roller to reach the collection concentrate area;the radial average magnetic field gradient of the magnetic system added to the auxiliary magnetic block is larger,the magnetic field has a greater depth of action,and the number of times the particles are flipped in the radial direction is more,which is more favorable for the magnetic particles outside the material layer to have more chance to approach the magnetic roller,which means that it can handle thicker layers and increase unit capacity and output while ensuring the sorting rate;the magnetic force of the magnetic particles in the magnetic system added to the auxiliary magnetic block is larger than the other groups at the peaks and troughs,and is more easily captured by the magnetic system.Secondly,for the problem of low agglomeration and low production capacity and low yield due to the agglomeration in the sorting chamber and the small thickness of the layer during the sorting process,the sorting chamber is modified according to the principle of Kamen vortex street,and the simulation software COMSOL Multiphysics is used to analyze the influence of different shape baffles and different cross-section bluffs on the flow field distribution of the sorting chamber,and the shape of the optimal baffle and the best crosssection bluff body was obtained.the coupling simulation of the gas-solid two-phase flow is carried out by the separation cavity formed by the good shape deflector and the best crosssectional shape bluff body.The conclusion is drawn that the uncontrollable turbulent flow will cause disordered vortices in the flow channel,which will cause the magnetic particles that have been captured are detached from the magnetic roller without reaching the outlet,increasing the difficulty of the magnetic roller for collecting magnetic particles,and the laminar vortex generated by the laminar flow is more stable and more uniform;the negative pressure is more likely to occur in the sorting chamber formed by the irregular baffle.The flow of gas along the flow channel increases the absolute value of the negative pressure,which is more conducive to the air entering the flow channel and pushing the particles to participate in the sorting operation;the velocity and eddy current at the two points in the sorting cavity formed by the irregular baffle have a larger difference between the peak and the trough,the velocity fluctuation is larger,the eddy current intensity is larger,which is more favorable for the magnetic particles outside the material layer to have more chance to approach the magnetic roller;when the gas bypasses the trapezoidal section of the bluff body,the velocity and eddy current at the two points are larger at the peak and trough,the velocity fluctuates more,the eddy current is stronger,the motion is stronger,and the average eddy current in the entire flow channel is consistent with it;the gas-solid two-phase flow is sorted in a sorting chamber formed by a trapezoidal section bluff body and an irregular baffle plate,which is more favorable for the magnetic particles on the outer side of the gas flow layer to be close to the magnetic roller,which means that it can process thicker layers,improve unit capacity and output under the premise of ensuring the sorting rate,and is more conducive to collision between particles to increase the looseness of gas-solid two-phase flow,reduce agglomeration and improve the grade of the iron fine powder.This research provides a certain method and idea for the processing and production of mine-type experimental equipment designed by the research group.It also provides a new direction for the improvement of the separation chamber of the magnetic separator for the experimental group.With the improvement and experimental verification of the magnetic separator,it is gradually applied to the mining area that is consistent with the working conditions in Inner Mongolia.