Effects of polarizer on the metals migration and transformation behaviors during the thermal treatment of discarded LCD panels

Thermal treatment has been proved as an efficient and promising method for LCD panel scraps pre-treatment and resource recycling. However, undesirable pollutants including polycyclic aromatic hydrocarbons (PAHs) and heavy metals tend to occur during the thermal treatment. To better understand the metals migration behavior and to illustrate the interaction effect between organics and metals, effect of the polarizer on the metals (Cr, In, Ni, Cu, Zn, Fe) migration and transformation behaviors was analyzed in this study. Results showed that polarizer, the main organic component in LCD panel, could enhance the metals migration behavior during the thermal treatment and also affect the metals speciation distribution in solid residue. The enhancement effect on metals migration rate was mainly deduced by the gas/volatile compounds from polarizer decomposition, while the metals speciation distribution in solid residue was mainly affected by the solid product from polarizer decomposition. The polarizer also showed increase effect on the potential risk of In, Cu and decrease effect on Fe in solid residue. The results suggest that reducing the organics content or adding solid carbon in treatment system would helpful to decrease the metals migration during thermal treatment process of discarded LCD panels. (c) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.