Properties and Reliability Evaluation of Consecutive Pyrolysis and Incineration Disposal Process for FR-4 Waste Printed Circuit Boards

Properties and reliability of using newly-developed pyrolysis and incineration process to dispose typical Waste Electrical and Electronic Equipment (WEEE) like motherboard of personal computer (MPC) and circuit board of Light Emitting Diode subtitle (CBLEDS) (model: FR-4) have been explored by utilizing large-scale self-developed 50.0 kg/h consecutive pyrolysis incinerator. First confined Pyrolysis Chamber (PC) is used to thermally degrade and gasify wastes into gaseous products and chars in low-oxygen level atmosphere first, and gaseous products are transmitted to second confined High-temperature Burning Chamber (HTBC) for further clean incineration in this setup. Diesel oil and pine wood were adopted as piloted ignitor and fuel in PC respectively. Disposed solid WEEE waste materials were mixed at the same mass ratio (wood: circuit board=3:1). The technical reliability (reflected by waste temperature of incinerator, combustion efficiency, gas residence time, thermal reduction rate, mass loss ratio and volume reduction ratio) was analyzed and evaluated, environmental pollution levels of 13 items like SO2 and NOx were inspected according to a series of Chinese Standards like GB/T16157-1996 and GB18484-2001. Results show flue gas peak temperature of MPC and CBLEDS in HTBC reach 910.0 ℃ and 1120.0 ℃, combustion efficiency in HTBC is as high as 99.90 %, gas residence time of pyrolysis in PC of both MPC and CBLEDS are 3.0 s, their thermally reduction rates of residues are 1.87 % and 1.76 %, mass loss ratios reach 85.80 % and 83.01 % and volume reduction ratios reach 78.06 % and 72.13 % respectively, the detection results of exhaust ringelman emittance hazardous gas and heavy metal content basically comply with atmospheric pollutant emission permit requirements, indicating FR-4 based WEEE can be disposed by consecutive pyrolysis and incineration process quite well with high temperature stability, technical reliability, combustion efficiency and friendly environmental safety.