Chlorinated Separation Of Indium Using Microwave Heating And Preparation Of Foam Glass From Waste Liquid Crystal Display Panels

With the sustaining increase in the application amount of liquid crystal displays worldwide and the upgrading of products,a large number of waste liquid crystal displays have been appeared.In order to solve the comprehensive processing technology problem of waste LCD,this paper provides a resourceful and harmless treatment for the recovery of indium and the reuse of glass substrates in waste liquid crystal displays.In this paper,the optimum process conditions for the chlorinated preparation of indium and glass substrates were explored by testing the parameters of the equipment,which provided an experimental basis and theoretical basis for the realization of the resource and harmless recycling technology of waste LCD panels.First,a single-mode microwave sintering furnace was designed in this experiment,which provided a heated bed by adding microwave absorbing medium to raise the temperature.The test results show that when the microwave power is set to 800w,and 30g silicon carbide is used as the absorbing medium,heating temperature can rise stably,and the thermal conversion efficiency is high.Subsequently,the optimal process conditions for the recovery of indium by microwave heating technology were explored.The experimental results for pure material In₂O₃ showed that the recovery rate of indium materials reached 98.91%when the temperature is 500?,the Cl/In molar rate is 8,and the heating time is 3min.For the recovery of indium material in the waste liquid crystal panel,on the basis of the ball mill pretreatment which achieves the ball ratio of 20:1,the ball mill speed of 300r/min,and the ball milling time of 20min,the recovery rate can achieve nearly 80%from the waste liquid crystal panels under the conditions:the chlorinating agent NH₄Cl with the glass powder mass ratio of 0.6,the chlorinating temperature is 500?and the heating time is 3min.Finally,the treated glass substrate powder was mixed with 0.5 wt.%of graphite powder,4wt.%Na₂SiF₆,4 wt.%Na₃PO₄,and then rise temperature to 875?at a rate of 15 K/min.After maintaining for 40 minutes,it was cooled to 600°C at a rate of 15 K/min for annealing and maintained for 20 minutes to obtain a foamed glass.The foamed glass obtained by the above method has a bulk density of 0.78 g/cm³,a mechanical compressive strength of 3.42 Mpa,a water absorption ratio of 0.41 wt.%,and a thermal conductivity of 0.052 w/m²·K.With the conclusion of this experiments,it is proved that recovery the indium from the waste LCD panels was effective,and preparation of foam glass from the glass substrate achieved resource recycling,which avoids the generation of toxic and harmful substances.This technology has advantages of environmental friendliness,energy saving and economy,and is worthy of industrialization promotion.The process can realize resource recycling and harmless treatment of the waste LCD panels.