Indium Recovery from Waste Liquid Crystal Display via Chloride Volatilization Process: Thermodynamic Computation

Yaoguang Guo 1

Qichao Zhang 1

Xiaoyi Lou 2

Huili Liu 1

Jiangbin Wang 1

Jie Guan 1,3, Email

Xin Xu

Xiaojiao Zhang 1

Yaguang Li

Yingshun Li 5

Zhanhu Guo 6, Email

1 Research Center of Resource Recycling Science and Engineering, School of Environmental and Materials Engineering, Shanghai Polytechnic University, Shanghai 201209, China

2 Key Laboratory of Control of Quality and Safety for Aquatic Products, Ministry of Agriculture, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, China

3 Shanghai Pudong Shuguang Research Center for High Environmental Treatment Technologies, Shanghai 20209, China

4 Shanghai Waigaoqiao Free Trade Zone Environmental Services Co.,Ltd., Shanghai, 200131, China

5 Shanghai Xin Jinqiao Environmental Protection Co., Ltd., Shanghai 201201, China

6 Integrated Composites Laboratory (ICL), Department of Chemical & Bimolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA

Abstract

With the increase of the scrap liquid crystal displays (LCDs), recycling indium from waste LCDs has captured an international attention. Chloride metallurgy is a promising method for indium recovery from LCD panels, due to the lower boiling point of indium chloride. In the present study, thermodynamic analyses of indium recovery from waste LCDs via chloride volatilization process by the HSC Chemistry software was carried out to understand the reaction mechanism between chlorinating agent and LCDs to avoid adverse factors, and simultaneously obtain the optimal conditions for the extraction of indium. The results show that the recovered indium from LCDs with HCl as the chlorinating agent from the PVC pyrolysis is feasible, with the chlorination temperature controlled between 134.49 and 554.25 oC, and the evaporation temperature higher than 490 oC, and simultaneously, the oxygen partial pressure controlled or under anaerobic conditions. As such, the influences of SiO2 , Al2O3 and Fe2O3 , contained in LCDs, can be ignored or avoided, and only CaO, K2O and Na2O would consume partial pressure of HCl gas, reducing the indium recovery reaction rate. The present study might provide important inspiration for indium recovery from waste LCDs via chloride volatilization process.

Indium Recovery from Waste Liquid Crystal Display via Chloride Volatilization Process: Thermodynamic Computation