废旧塑料分选技术研究进展

Research progress in separation technology of waste plastics

中国是世界上最大的塑料生产国和消费国,大量废旧塑料不断堆积或丢弃在环境中,对自然生态系统造成了严重危害,废旧塑料的合理处置和再生利用迫在眉睫。根据不同塑料及其杂质之间的物理化学性质差异制定高效的分选方法,可以为废旧塑料的循环利用创造条件。本文系统梳理了废旧塑料和其他材料之间的解离技术,主要有热解、溶胀分选、涡流分选、重选和磁选等;废旧塑料的预处理也很重要,主要包括清洗和破碎两个步骤;混合废旧塑料分离技术可分为两类:一类是基于塑料基材性质的直接分选,如密度分选、选择性溶解、泡沫浮选、静电分选等;一类是基于光谱技术的间接分选,如颜色分选、X射线分选、红外光谱分选、激光光谱分选等。废旧塑料分离工艺主要包括废旧日杂塑料的分选、废旧手机电路板中塑料的分选、废弃医用输液瓶/袋的分选、废旧电器的分选等。分析了各种分选工艺的优缺点,在理顺各类分选方法的基础上制定含塑固废分选的原则流程,可为废旧塑料最大程度的循环利用提供参考。

China is the world's largest producer and consumer of plastics,with a large amount of waste plastics constantly piling up or discarded in the environment,causing serious harm to natural ecosystems.Therefore,the rational disposal and recycling of waste plastics are urgent.Developing efficient sorting methods based on the differences in physical and chemical properties between different plastics and their impurities can create conditions for the recycling of waste plastics.This paper systematically reviews the dissociation techniques between waste plastics and other materials,mainly including pyrolysis,swelling separation,eddy current separation,gravity separation,and magnetic separation;The pre-treatment of waste plastics is also important,mainly including two steps of cleaning and crushing;The separation technology of mixed waste plastics can be divided into two categories:One is direct separation based on the properties of plastic substrate,such as density separation,selective dissolution,foam flotation,electrostatic separation,etc;One type is indirect sorting based on spectral technology,such as color sorting,X-ray sorting,infrared spectral sorting,laser spectral sorting,etc.The separation process of waste plastics mainly includes the sorting of waste daily plastics,the sorting of plastics in waste mobile phone circuit boards,the sorting of waste medical infusion bottles/bags,and the sorting of waste electrical appliances.The advantages and disadvantages of various sorting processes is analyzed,and the principle process of plastic-containing solid waste sorting is formulated on the basis of rationalizing various sorting methods,which can provide reference for the maximum recycling of waste plastics.