Research On The Complete Set Technology And Theory Based On The Recovery Of Metal From Waste Printed Circuit Boards

This paper studies the status of electronic wastes flooding in China, introducing its harmfulness and the serious situation, emphasizing that it is urgent to recover the electronic waste safe and effective. Only in this way, can we protect our environment for the survival, can we recycle available resources from the rubbish, turning the waste into treasure. This paper studies the status of recycling waste printed circuit boards domestic and foreign, through the comparison of different recycling methods, found that the physical and mechanical method has certain advantages, more suitable for today.On this basis, this paper proposes a method of recycling waste printed circuit board with "roller extrusion shear coarse crushing + hammer type wet fine + liquid-solid fluidized bed separation", and validate the feasibility of recycling and recycling effect of the method by experiment. Compare of different crushers’ crushing effect of waste circuit boards, founding that the crusher with shear and impact force is better. Therefore,design the cutting tool and hammer of own-made two grade crushing machine, make the tool with shear and impact force in coarse crushing process, make the hammer with bigger shock force at the same time, and then crushing waste printed circuit boards in the own-made two grade crusher, study the situation of materials’ size distribution,metallic and nonmetallic dissociation and so on; though comparing the broken effect of dry and wet broken, prove that wet crushing can reduce the superiority of crushing cavity temperature, reduce the secondary pollution; and then through the comparison tests of hammer with different perspectives, finding out the influence rule of the angle of.hammer broken effect. Finally using self-made liquid-solid fluidized bed separation system to separate the different grades materials after broken, respectively, by controlling the rising water flow velocity and feeding quantity to study the effects of separation effect, and optimize the rising velocity of water flow and feeding quantity to achieve the optimal separation effect.The tests proved that: own-made crusher can crush the printed circuit boards very good, wet fine can reduce the working temperature of crusher, and can reduce dust and secondary pollution in the crushing process, verified the effect of hammerhead with different angels to crush printed circuit boards, and get an empirical formula about theeffect of own-made crusher. In addition, in the process of liquid-solid fluidized bed separation, finding that with the increase of rising water speed, the recovery is on the decline of the metal, metal grade is on the rise; And within a certain range, the separation effect of feeding quantity the impact is not big, but the metal recovery rate has a tendency to decrease, the tendency of increase with the metal grade, in order to make the metal recovery and metal grade have reached a good level, optimize the rising water speed and feeding quantity to achieve a good separation effect.