Simulation On Separation Process Of The Three-product Magnetic-separation Column

The traditional magnetic separation column makes full use of the magnetic force generated by the alternating magnetic field and the fluid drag force of the rotating water flow to produce the "agglomeration dispersion agglomeration" effect on the strong magnetic particles in the magnetic separation process,effectively reducing the inclusion of non-magnetic gangue in the magnetic aggregates,but there are also problems such as the loss of fine magnetite and large water consumption.On the basis of retaining the advantages of the traditional magnetic separation column,the three product magnetic separation column has improved the magnetic field and flow field structure according to the differences in magnetism and particle size between magnetite particles.The coarse separation area,cyclone dispersion area and concentration area have been designed respectively.By adjusting the magnetic field and flow field parameters,three kinds of products can be obtained,namely,fine ore,middling ore and tailings.In recent years,computer simulation has promoted the rapid development of magnetic separation technology.Due to the complexity and diversity of ore properties and process flow,there are many process problems that need to be solved in the practical application of magnetic separation equipment.For ore materials lacking the support of actual production data,special magnetic separation equipment research and test are required to demonstrate the scheme.Using mathematical modeling and process simulation technology is very beneficial to optimize the design of three product magnetic separation column,shorten the product development cycle and reduce the development cost.In this paper,based on the design principle of three product magnetic separation column,an overlapping ball model of magnetite particles is established by using the EDEM-API technology.Combining FEM(finite element method),CFD(computational fluid dynamics)and DEM(discrete element method,The narrow necessary conditions for effective collection of different ore components are established,and the simulation results are verified through the actual separation test.The main research theories and conclusions are as follows:(1)The discrete element model of particles is established using the discrete element software,and the overlapping ball model inside the discrete element software is used for the shape,and the parameters of the particle model are controlled according to the relationship between particle grade and density,so that its appearance and properties are close to the actual test requirements;(2)The magnetic system structure of the three product magnetic separation column is established by using the finite element software,and the coil attribute is set to generate an effective magnetic separation field in the three product magnetic separation column;(3)The separating cylinder of three product magnetic separation column is divided into ten areas in the radial direction.The magnetic field intensity on ten circles and centers is taken as the standard,and the magnetic field intensity on eleven straight lines is taken as the representative in the axial direction.The internal magnetic field of three product magnetic separation column is established.Finally,the curve fitting tool in MATLAB is used to combine the obtained magnetic field intensity with the coordinate points inside the three product magnetic separation column model to achieve the correspondence between coordinates and magnetic field intensity;(4)The obtained magnetic field intensity is distributed to the three product magnetic separation column model of the discrete element software by using the code secondary development,and the specific magnetization coefficient curve is given to the particles to make them have magnetic properties;(5)The finite element software is used to establish the flow field structure of the three product magnetic separation column.After the model is imported into Fluent,its flow field parameters are set to make the water flow fill the inside of the model.The simulation of swirling flow under fixed conditions is completed.The UDF file is used to program the size and direction of the flow velocity of each coordinate point inside the model into the TXT file.The secondary development is used to obtain the swirling flow data,which is assigned to the inside of the model of the discrete element software,Make the swirl data correspond to the internal coordinates of the model;(6)The magnetic field and flow field are coupled inside the discrete element software,the basic properties of particles are set,and the whole separation process is completed.Under the condition that the TFe grade of ore feed is 61.42%,the TFe grades of concentrate,middling and tailings obtained from the simulation test are 63.60%,58.44% and 29.63% respectively.According to the appropriate operating parameters obtained in the simulation process Φ 159 type three product magnetic separation column was used for the actual separation test of a magnetite ore.The TFe grades of concentrate,middling and tailings were 65.55%,42.58% and 24.23% respectively.The relative error between the simulation test and the actual test was within 3%.In this paper,a set of basic paths for separation simulation by coupling magnetic field and flow field is established,which provides a theoretical basis for the subsequent magnetic separation process and the optimization of magnetic separation equipment.