废旧电脑电路板预处理及常规和微波热解特性研究

Pretreatment of waste computer circuit board and characteristics of conventional and microwave pyrolysis

废旧印刷电路板中含有丰富的金属及非金属资源,具有较高的资源回收价值与潜在环境危害性。在常规和微波热解条件下,对废旧电脑电路板脱锡预处理及相关热解条件对热解产物的分布规律及影响机制进行研究。结果表明:脱锡预处理对废旧电脑电路板的热解有正向影响,可以使废电路板中的有机材料热解更充分,脱锡预处理后Sn含量从4.10%降低至1.54%,Sn的回收率达68.49%;在常规和微波热解条件下,升高温度可以获得更多的液体和气体产物,但相同温度下微波热解得到的固体产物更多,常规热解后铜含量从热解前的19.17%升高到25.37%,微波热解后铜含量从热解前的19.17%升高到23.32%,铜的回收率达到99.22%以上;热解后绝大部分的溴元素进入到热解油与热解气中,微波热解油中酚类物质含量大于常规热解,呋喃类物质少于常规热解,常规和微波热解气中H_(2)、CO、CH_(4)总量分别达到76.4%和80.7%,热解气体热值分别为18.78 MJ/Nm^(3)和19.97 MJ/Nm^(3),热解气热值介于煤气与天然气之间,可作为燃气使用。综合对比常规热解与微波热解,微波热解金属回收率更高,热解气体中呋喃类物质更少、热解气热值更高,更有利于电子废弃物中有价金属的综合回收利用。

Waste printed circuit boards are rich in metal and non-metal resources, which have high resource recovery value and potential environmental hazards. In this study, under the conventional and microwave pyrolysis conditions, the influence of the detinning pretreatment and related pyrolysis conditions on the distribution and mechanism of pyrolysis products were studied. The results show that detinning pretreatment has a positive effect on the pyrolysis of waste computer circuit boards, which can make the organic materials in the waste circuit boards pyrolyze more fully. After detinning pretreatment, the Sn content is reduced from 4.10% to 1.54%, and the recovery rate of Sn can be reached 68.49%. Under conventional and microwave pyrolysis conditions, more liquid and gas products can be obtained with the temperature increasing, but more solid products can be obtained by microwave pyrolysis at the same temperature.After conventional pyrolysis, the copper content increased from 19.17% before pyrolysis to 25.37%, and after microwave pyrolysis, the copper content increased from 19.17% before pyrolysis to 23.32%.And the recovery rate of copper is over 99.22%. After pyrolysis, most of the bromine element enters the pyrolysis oil and pyrolysis gas. The content of phenolic in microwave pyrolysis oil is greater than that of conventional pyrolysis, and the content of furans is less than that of conventional pyrolysis. The pyrolysis gas contains a large amount of combustible gas. The total amount of H_(2), CO and CH_(4) in the conventional and microwave pyrolysis gas reach 76.4% and 80.7%, respectively. The heating value of the pyrolysis gas is 18.78 MJ/Nm^(3) and 19.97 MJ/Nm^(3), respectively. The calorific value of pyrolysis gas is between coal gas and natural gas and can be used as gas. Comprehensive comparison between conventional pyrolysis and microwave pyrolysis, microwave pyrolysis has a higher metal recovery rate, less furans in the pyrolysis gas, and a higher calorific value of the pyrolysis gas, which is more conducive to the comprehensive recovery of valuable metals in electronic waste use.