Numerical Simulation Of The Mixing And Kneading Process Of Carbon Anodes For Aluminum Electrolysis

Mixed kneading is the core process in the manufacture of aluminum electrolysis prebaked anode.The mixing effect not only affects the anode quality directly,but also is closely related to the economic benefit of aluminum electrolysis.At present,due to the mixed kneading process in the closed kneading machine,the lack of reasonable characterization of the material properties of the mixed kneading process,as well as the corresponding parameter monitoring,resulting in the judgment of the end point of the mixed kneading still rely on the site experience,with great uncertainty,is an important cause of the anode quality fluctuations.In this paper,the study of kneading process through discrete element simulation is helpful to deepen the understanding of kneading mechanism and provide theoretical basis and guidance for optimizing the production process.Based on EDEM software,the model of kneading machine and mixture particles is established in this paper.The numerical simulation of kneading process is studied.Using the criterion of discrete coefficient,contact ratio,coordination number and relative standard deviation for macroscopic uniformity and bonding uniformity respectively,and using the torque and power of mixing knife of mixing machine as the parameters of real-time monitoring of mixing state,the influence of mixing knife speed and viscosity on mixing process of mixing machine was explored.The results show that:(1)Within a certain rotational speed range,high rotational speed can accelerate the movement speed of each unit of the mixture and make the mixing more intense.It is further proved that the mixing quality of the mixing machine is better at higher rotation speed in dry mixing and wet mixing stages through the changes of the discrete coefficient,contact ratio,coordination number and relative standard deviation.However,the analysis of energy consumption according to load torque shows that higher speed may increase energy consumption in dry mixing.(2)Viscosity has a great influence on the wet mixing process.Under too low viscosity,the adhesion between particles is not obvious,and the torque of the stirring tool is low.With the increase of viscosity,the bonding property between particles increases gradually,and the torque of stirring tool increases significantly.Too high viscosity will lead to too large agglomeration of particles,too large movement area,and the contact area with the stirring knife is reduced,but the torque will be reduced,thus affecting the wet mixing effect;The ideal viscosity range is the particle surface energy of 3.75-5.0J/m~2.