E-waste refers to electrical appliances or electronic equipment that are abandoned and no longer used, mainly including household appliances such as refrigerators, air conditioners, washing machines, televisions and electronic products such as computers.
There are many kinds of electronic wastes, which can be roughly divided into two categories:
One category is waste electronic products with relatively simple materials and less harm to the environment, such as household appliances such as refrigerators, washing machines, air conditioners, medical and scientific research appliances, etc., and the disassembly and disposal of such products are relatively simple.
the other category is the waste electronic products with complicated materials, which are harmful to the environment, such as lead in the picture tubes of computers and televisions, arsenic, mercury and other harmful substances in computer components, arsenic, cadmium, lead and other toxic substances with persistent degradation and bioaccumulation in the raw materials of mobile phones.
Extended information
Treatment methods of electronic waste
1. Chemical treatment
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 subjected to a series of processes such as extraction, precipitation, replacement, ion exchange, filtration and distillation to finally obtain high-grade metals. However, the use of strong acid and highly toxic fluoride in the chemical treatment process will produce a lot of waste liquid and discharge toxic gases, which will do great harm to the environment.
2. Pyrolysis
Pyrolysis is a method of burning, melting, sintering and melting electronic waste to remove plastics and other metals rich in organic components. Pyrolysis will also cause serious harm to the environment. From the aspects of resource recovery and ecological environment protection, these methods are difficult to popularize.
3. Mechanical treatment
The mechanical treatment of electronic waste is a method of sorting by using the differences of physical properties between components, including disassembly, crushing, sorting and other steps. After sorting, the recycled materials such as metal, plastic and glass can be obtained respectively through subsequent treatment. This treatment method has the advantages of low cost, simple operation, not easy to cause secondary pollution, easy to realize scale, etc., and is a hot spot developed by various countries.
4. Microbial treatment
Leaching precious metals such as gold by microorganisms is a new technology for extracting precious metals from low-content materials, which was studied in 198s. Other non-precious metals in precious metal alloys, such as gold, are oxidized into soluble substances and enter the solution by microbial activities, so that the precious metals are exposed for easy recovery. Biotech extraction of precious metals such as gold has the advantages of simple process, low cost and simple operation, but the leaching time is long.