Analysis of waste PCB circuit boards and recycling methods

With the industrialization and scale of PCB processing and the wide application of electronic products, more and more electronic wastes are generated and manufactured in the production and living activities of human society.

Waste PCBs contain heavy metals such as lead, mercury, and hexavalent chromium. If discarded at will, PCBs also contain toxic chemicals such as polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE) as flame retardant components. It will not only pollute the environmental soil and water resources, potentially endanger human health, but also cause wasted resources that are difficult to recycle. There are nearly 20 kinds of non-ferrous metals and rare metals on the waste PCB, which has a high economic value of recycling.

Therefore, it is particularly important to properly dispose of waste PCB circuit boards.

Today we talk about several ways to deal with electronic waste:

1 Physics

According to the different physical properties of the PCB, it is recycled by physical and mechanical means.

1.1 Broken

Mechanically break the PCB, disintegrate and separate its metal and organic matter, and improve the sorting efficiency. When the crushed particles reach 0.6mm, the metal can basically achieve 100% dissociation, but the choice of crushing method and series depends on the subsequent process.

1.2 Sorting

The crushed materials, according to their differences in physical properties such as density, particle size, electrical conductivity, magnetic permeability and surface characteristics, can be processed by wind shaker technology, flotation separation technology, cyclone separation technology, floating-sink separation and eddy current separation technology. sorting.

2 Supercritical technology treatment method

This method does not change the chemical composition of the PCB material. Through pressure and temperature, the supercritical fluid is dissolved separately, and then extracted, separated and purified. Compared with traditional extraction methods, supercritical CO2 extraction is more environmentally friendly, convenient for separation, low toxicity, little or no residue, and room temperature operation.

Supercritical processing technology is not without its flaws. For example, the entrainer used in the extraction is harmful to the environment; the high-pressure and high-temperature extraction method requires high equipment and large energy consumption.