Research on Metals Recycling from Waste Printed Circuit Board by Mechanical Processing of Wet Crushing and Wet Separation
Reutilization of waste printed circuit boards (PCB) can not only prevent potential environmental pollution,but also achieve recycling of secondary resources.Study on recycling of discarded PCB belongs to the front edge of environmental pollution prevention and resource recycling.In order to effectively crushing waste PCB,and solve the problem of secondary pollution of fugitive odor and dust during the crushing process,a wet impacting crusher was adopted to achieve comminution liberation of PCB in water medium.96.79% of the crushed yield was distributed in -2mm,and metal took 97.18% in this grade of production.Size distribution of PCB panicles was characterized double peaks at the sizes of -1+0.5mm and -0.074mm.A double Rosin-Rammler function,is called DRR function,is put forward to describe the size distribution of PCB particles.The DRR function of cumulative weight percentage oversize of PCB was non-liner fitted by self-defining DRR function of the Origin 7.0.The evaluation indexes of the fitting results are the correlation coefficients R2 of 0.9994 and residual E of 0.18671,those show that DRR function is perfectly accurate.Based on the research the mechanical separation and material properties of PCB,a wet process of reclaiming metals from PCB using a new style separator tapered diameter separation bed (TDSB) in water medium was designed,and the related separation mechanism was studied.The fluid field of the tapered diameter separation equipment was simulated by the Ansys Flotran software,the variation laws of the velocity in each position in the fluid field as well as the equation of axial distribution sectional max velocity were analysed according to the simulation result,the stress change and motion trajectory of the pellet in the certain fluid field were analysed.The results show that the expanding tubular structure of the varied diameter separation bed indicates gradually decreasing velocity of water flow along the axis,assuming a certain angle in the bed,as a result of the gravitys influence,and there was corresponding change to the distribution of the flow velocity,thus the whole formed a special fluid field where velocity variations exist in different positions.When the material passed through the fluid field along with the water flow,as a result of the difference to the particle density,the granularity and the shape,there would appear the difference to the motion trajectory as well as the movement distance under the action of the fluid:The lower density materials discharge along with water flow,but the higher density materials would be kept in bottom of the bed and discharge through material mouth.Therefore,light and heavy products were separated effectively according to the density.Using tapered diameter separation bed to process the -1mm size crushed material of waste printed circuit boards,with the discharge of water 5.5m3/h,feed-rate of the material 250g/min and with an obliquity 35°,product with 93.92% in integration efficiency and 93.73% in recovery ratio of the metal were obtained by the primary separation.Compared with other mechanical methods,the range of panicle size was broaden using the TDSB to recovery metals from PCB,and lower limit size of separation almost approach to 0.An innovative process of wet impact crushing+ classifying+ tapered diameter separationrecycling metals from waste PCB was developed.
Waste printed circuit boards Wet impact crushing Tapered diameter separation bed Simulation
Y.M.Zhao C.L.Duan H.J.Zhang Y.Q.He J.F.He B.F.Wen
School of Chemical Engineering and Technology,China University of Mining & Technology,Xuzhou,China
国际会议
XXIV International Mineral Processing Congress(第24届国际矿物加工大会)
北京
英文
3765-3773
2008-09-24（万方平台首次上网日期，不代表论文的发表时间）