Numerical Simulation And Process For The Rotating Separation Enrichment Of Metallic And Non-metallic Materials In WPCBs

WPCB, which is the important part of electronic waste, contains the mTetal content several times even hundred higher than ordinary deposits. But if WPCBs were discarded strictly, the environment would be polluted seriously by the toxic and hazardous substances.Traditional recycling methods like Pyrometallurgy and wet metallurgy,of which the main goal is recycling the metal especially precious metals, are not emphasis on other materials. They cause so serious secondary pollution as to the increasing requirements of environmental protection can not be met. This thesis is supported by "Eleventh Five-Year" National Science and Technology Support Program. It combines with the gas-solid multiphase flow theory and proposed cyclone separation process for recycling metallic and nonmetallic materials. The main research work is reflected in the flowing aspects:(1) Proposed rotating airflow separation process on the circuit board recycling, and established a reasonable cyclone gas-solid single particle motion characteristics by using aerodynamics, hydrodynamics theoretical principles. The balance particles around the sorter axis for circular motion without sorting enriched in the system. The enriched state of the non-equilibrium particles separation, depends on the relative relationship between the axial movement characteristic time (τz) and the radial movement characteristic time (τr).(2) Based on the complex movement of the cyclone gas-solid flow characteristics, and combined with the circuit board particles sorting process characteristics, with the role of the interaction between the particles and the particles flow field, ignored the heat transfer effect which was decided by the characteristics of the particles sorting circuit board process, in order to establish the averaged equations which can describe the gas-solid multiphase flow. The equations was closed by using κ-ε/RNG model. Cyclone separation efficiency and sorting efficiency calculation were proposed.(3) The main effective factors of the separation efficiency of the cyclone separator is studied through experiments. The experimental results with numerical results are in good agreement, which proved the numerical model and the separation efficiency model are correct and reasonable. And the related industrial equipment have been put into operation in Tianjin He Chang environmental technology Co, Ltd., the effect is significant.(4) The recovery process model of cyclone sorting is established, based on the studying for the cyclone sorting process of waste circuit boards. By studying and analyzing the input influencing factors of the model, the thesis concludes than the particles size and impeller speed are the main factors of the process model, the suck air volume and speed of the feed are less affected. And then, using Central composite experimental to study the optimization problem of WPCB cyclone sorting, the result shows that when the particle size of0.179mm, impeller speed for193.5r/min, the combined effect achieves optimal. At the same time, the theoretical calculations of the regression equation are agree with the range according to the contour map, and also are very approximated with the experimental results. Proving that the combined effect of the WPCB recycling process by cyclone sorting evaluation is correct.