Electronic waste disposal

1.什么是电子垃圾？

“电子废弃物”又称“电子垃圾”，（英文e-waste、waste electronic equipment）。废弃不用的电子设备都属于电子废弃物。电子废弃物种类繁多，大致可分为两类：一类是所含材料比较简单，对环境危害较轻的废旧电子产品，如电冰箱、洗衣机、空调机等家用电器以及医疗、科研电器等，这类产品的拆解和处理相对比较简单；另一类是所含材料比较复杂，对环境危害比较大的废旧电子产品，如电脑、电视机显像管内的铅，电脑元件中含有的砷、汞和其他有害物质，手机的原材料中的砷、镉、铅以及其他多种持久性和生物累积性的有毒物质等。

2.目前国内的处理方法

（1）化学处理

The chemical treatment of electronic waste is also called wet treatment. The crushed electronic waste particles are put into acidic or alkaline liquid, and the leaching solution is then extracted, precipitated, replaced, ion exchanged, filtered and distilled to obtain high-grade metals. However, in the process of chemical treatment, strong acids and highly toxic fluorides will be used, which will produce a large amount of waste liquid and discharge toxic gases, which will do great harm to the environment.

（2）火法处理

Pyrotechnic treatment is a method of incinerating, smelting, sintering, melting, etc. of electronic waste to remove metals enriched in plastics and other organic components. Fire treatment will also cause serious harm to the environment. From the aspects of resource recovery and ecological environment protection, these methods are difficult to promote. Guiyu town in Guangdong Province in China has adopted these two treatment methods that are relatively harmful to the environment, which have brought serious impact on the local environment and sustainable development.

（3）机械处理

Mechanical treatment the mechanical treatment of electronic waste is a method of sorting by using the differences in physical properties between components, including disassembly, crushing, sorting and other steps. The materials after sorting and processing can be obtained from recycled raw materials such as metal, plastic, glass and so on through subsequent treatment. The disassembly of electronic waste is usually done manually to recycle the electronic components that have been tested and useful. However, due to the large number of electronic components in electronic waste and the complex combination mode, the manual treatment efficiency is very low.

（4）微生物处理

Leaching gold and other precious metals by microorganisms is a new technology for extracting precious metals from low content materials, which began to be studied in the 1980s. The activities of microorganisms make other non precious metals in precious metal alloys such as gold oxidize into soluble substances and enter the solution, exposing precious metals for recycling. Biotechnology extraction of gold and other precious metals has the advantages of simple process, low cost and simple operation, but the leaching time is long.

• Treatment of electronic waste by plasma gasification technology

Plasma gasification technology uses plasma torch to heat waste to ultra-high temperature. Under the action of ultra-high temperature and reactive particles, waste molecules are completely decomposed into atomic states, and organic matter is decomposed into simple gas molecules to form syngas (mainly Co, H2), which can be used as fuel or chemical raw materials; Inorganic substances melt to form vitreous slag (mainly composed of silicate and metal), which can be used to recover metals and building materials. Compared with the traditional pyrolysis and gasification treatment method, the high energy density and high temperature of the plasma make the waste reaction speed very fast, which does not depend on the existence of free radicals. It can decompose organics more effectively without producing dioxins. At the same time, there is no fly ash to avoid secondary pollution, and finally realize the complete harmless treatment of toxic and harmful substances, with the waste removal efficiency of more than 99%.