Research On High Efficiency Separation Process Of Different Components And Equipment Development In Discarded PCB

The content of copper in waste circuit boards is very high.Even if compa red with fine copper,the content of copper is often 10 times higher.At the sa me time,the contents and types of other metals in used circuit boards are also very rich,including many precious metals such as Au and Ag,so waste circui t boards have been called "urban mines." At the same time,waste circuit boar ds contain heavy metal elements such as lead,cadmium,brominated flame retar dants and polychlorinated biphenyls.If they are discarded or buried,it will cau se serious pollution to the surrounding environment.Because the used circuit b oard itself has the characteristics of complex structure,various types,large indi vidual differences,and the incompatibility of metal and nonmetal bonding,it is very difficult to recycle them.In this paper,the physical recycling method thr ough dismantling,crushing,wind separation,high pressure electrostatic separati on and other processes is used to recycle resources,and the process paramete rs are also studied.In this paper,based on the hot oil dismantling method,a set of thermal o il dismantling equipment was developed.The synthetic heat-conducting oil was used as the heating medium,which can effectively solve the problems that the heating temperature is difficult to control and the heating temperature is unev en,Solder oxide oxidation is difficult to recycle and generate a series of issue s such as toxic and hazardous substances by traditional dismantling method..U sing the developed hot oil dismantling device,heating temperature(?),residen ce time(min),and motor rotation speed(rpm)were selected as three influenci ng factors and an orthogonal test was designed.By analyzing the test results,i t is found that when the temperature is 250°C,the residence time is 20 minu tes,and the motor speed is 300 rpm,the dismantling effect is best.In the crushing experiment,the crushing experiments were performed on th e disassembled and undisassembled circuit boards of the same quality,and the particle morphologies of the two circuit boards after crushing were analyzed,a nd it was found that the shape of the disassembled circuit boards was with reg ularities.Most of the metallic particles are spherical,non-metallic particles are mostly strips and uniform in size.Then the two groups of scraped circuit boar d particles were screened into six grades by electric vibrating screen: Grade 1(+0.8 mm),Grade 2(-0.8+0.6 mm),Grade 3(-0.6+0.45 mm),Grade 4(-0.45+0.3 mm),grade 5(-0.3+0.15 mm),grade 6(-0.15 mm).After the statistics of t he particle size of the two groups after screening,it was found that the disintegrated waste circuit boards had less distribution of the powder particles after p ulverization than the undisassembled waste circuit boards at the first-order parti cle size(+0.8 mm)and more distribution at the 6-level particle size(-0.15 m m).The cyclone separator was used to sort the two sets of circuit board parti cles.The results showed that the greater the frequency of the fan was,the gre ater the sorting efficiency would be.When the frequency of the fan is the sam e,the particle size of the circuit board after disassembling is not much differe nt due to quality difference,and the centrifugal force is similar which reduced the separation efficiency.So after dismantling the circuit board particles,furth er dismantling is necessary.This paper uses high-voltage electrostatic separation method to sort the selected circuit board particles,which made metal and non-metal completely separated.