Screening Mechanism Of Ultrafine Particles With Ultrasonically Assistance

Screening is an important technology for separation particles widely used in metallurgy,mining,chemical,pharmaceutical and other industrial fields.Ultrafine particles screening is a more complicated process,there is a strong van der waals force between the particles,with strong adsorption,easily binds to agglomerates and clogged the sieve,making screening inefficient.Most of the ultrasonic auxiliary screening equipment in domestic market are designed blindly because of the lacking of the ultrasonic auxiliary screening mechanism.So in this project,the mechanism of the ultrasonic auxiliary screening of fine powder material is studied.The main contents of this paper are as following three aspects:(1)Firstly,the dispersion mechanism of ultrafine particles agglomeration with the ultrasonic is theoretically analyzed.Combined with DLVO theory,and according to the energy and force produced by van der waals force and ultrasonic vibration in the screening process,the energy balance model and stress model of particles are established.Secondly,the dynamics and kinematics of ultrasonic vibration sieve are analyzed,and the movement of the ultrafine particles with the action of vibrating screen vibration and ultrasonic vibration are analyzed;(2)The agglomeration of ultrafine particles and the dispersion process with ultrasonic vibration are simulated in EDEM.Simultaneously,the stratification and the sieving process of particles are simulated.The influence of the layering process with different shape particles and the delamination effect of ultrasonic vibration are compared.Analyzed and simulated the influence of the sieving of material particles with different vibration parameters.Explored the stratified sieving mechanism of material particles,and obtained the optimum vibration parameters of material particles in the screening process;(3)Taking silicon powder as the research object,experiments were carried out to verify the mechanism of ultrasonic assisted disintegration of materials and adsorption.The results show that ultrasonic vibration can effectively break up particle agglomerates and solve the problem of sieve blockage,so as to significantly improve the screening efficiency.Simultaneously,Verified the influence of the screening efficiency with different vibration parameters through experiment.the optimal combination parameters of the silicon powder material in the sieving with vibrating sieve vibration and ultrasonic vibration are obtained.