废弃印刷线路板热解过程中溴的转化

Conversion of bromine during the pyrolysis of waste printed circuit boards

利用热重分析仪和管式炉在氮气气氛下进行废弃印刷线路板热解实验,研究了热解特性以及在热解过程中HBr的脱除和溴的转化.分别选用Ca(OH)2和CaCO3作为添加剂与印刷线路板粉末进行混合热解实验,研究了不同添加剂、Ca/Br摩尔比、温度的影响.实验结果表明,当添加剂为Ca(OH)2,Ca/Br摩尔比大于4∶1,723 K时,能够高效地脱除HBr并将印刷线路板中的有机溴转化为固体产物中的无机溴.当Ca/Br摩尔比为9∶1,723 K时,96.33%的溴已经转化为无机溴,其中99.88%的无机溴存在于固体中,有利于热解产物的利用以及溴的回收.

The pyrolysis characteristics as well as HBr removal rate and bromine conversion rate during the pyrolysis of printed circuit boards （PCB） were investigated by using thermal gravimetric analysis （TGA） apparatus and quartz tube furnace for pyrolysis experiments under nitrogen atmosphere. Calcium hydroxide and calcium carbonate were used as additives with PCB powder in co-pyrolysis experiments. The effects of additives, Ca/Br molar ratio and co-pyrolysis temperature were studied. The results indicated that when the additive is calcium hydroxide, the Ca/Br molar ratio is larger than 4 ： 1, and the pyrolysis temperature is 723 K, the pyrolysis has high HBr removal rate and high conversion rate of organic bromine of PCB to inorganic bromine. When the Ca/Br molar ratio is 9 ： 1 and the pyrolysis temperature is 723 K, 96.33% of the bromine is converted to inorganic bromine, 99.88% of which is in solid. This result helps to the use of pyrolysis products and the bromine recovery.