The contradiction of energy, resource and environment from waste liquid crystal display (LCD) panels is becoming more and more prominent because it contain both harmful liquid crystals and valuable metal indium. However, scarce researches have considered how to separate liquid crystals and recycle indium from waste LCD panels by an environment-friendly process. In this work, an integrated technological process to recycle energy and valuable resource from LCD panels is proposed. Firstly, a stripping product enriched liquid crystals and indium is gained by a mechanical stripping separation. Then, based on a series of pyrolysis separation, vacuum chlorinated separation and substitution reaction, concentration of indium is increased to 36 wt % in final product from 0.02 wt % in waste LCD panels. Several highlights were summarized as follows: (i) Feasibility, principle and reaction mechanism was studied to understand this integrated process. (ii) For pyrolysis process, separation rate of liquid crystals approached 82.06% under optimized parameters by response surface methodology. For vacuum chlorinated process, recovery rate of indium can reach 97.16%. This technological process is quite significant in accordance with the "Reduce, Reuse and Recycle Principle" for solid waste and further provides a new opportunity for sustainable development of LCD markets. (C) 2017 Published by Elsevier Ltd.

In the past, most of technologies adopted whole crush for waste LCD panels to treat liquid crystals and indium but had low recovery due to its low concentration. In this work, a mechanical stripping process was proposed firstly to gain stripping product enriched liquid crystals and indium. Liquid crystals are enriched from 03 wt% in waste LCD panels to 53 wt% in the stripping product. Likewise, indium is enriched from 0.02 wt% to 7.95 wt. Liquid crystals in stripping product should be removed in advance since it is disadvantage for indium recovery. This study can successfully remove liquid crystals by pyrolysis process. The results were summarized as follows: (i) Liquid crystals in waste LCD panels were mainly TFT type liquid crystals by thermal gravimetric analysis and chromatograph-mass spectroscopy. (ii) Liquid crystals can be well separated under optimized condition of 873 K, 40 min and 2 L/min N-2 flow rate. Oil and gas produced in pyrolysis process can be reused as energy and fuel. (iii) Pilot scale experiments were utilized to assess the actual effect of pyrolysis separation; decomposition rate of liquid crystals can reach 80%. It gives some valuable information for industrial separation of liquid crystals and provides a necessary preparation for further recovery of indium. (C) 2017 Published by Elsevier Ltd.