Waste PCB Boards Recycling
Why recycling pcb circuit board is important?
Wastes from electric and electronic equipments (WEEE) show an increasing upward tendency. A record 53.6 million metric tonnes (Mt) of electronic waste was generated worldwide in 2019, up 21 per cent in just five years, according to the UN’s Global E-waste Monitor 2020. The report also predicts global e-waste – discarded products with a battery or plug – will reach 74 Mt by 2030, almost a doubling of e-waste in just 16 years.
PCBs have a ratio consisting of 40% metals, 30% organic materials, and 30% ceramics. Therefore, recycling processes recover approximately 99% of copper, copper-beryllium alloys, beryllium oxide, aluminum, tin, gold, silver, platinum, palladium, and lead from a PCB board. Only 17.4 per cent of 2019’s e-waste was collected and recycled. This means that gold, silver, copper, platinum and other high-value, recoverable materials conservatively valued at US $57 billion – a sum greater than the Gross Domestic Product of most countries – were mostly dumped or burned rather than being collected for treatment and reuse.
Besides, a significant proportion of WEEE is constituted by PCBs, which is a health and environmental hazard, containing toxic additives or hazardous substances such as mercury. If not properly disposed of, it could cause great damage to the environment.
Waste PCB circuit board recycling methods
1. Heat treatment method
The heat treatment method is mainly a method of separating organic matter and metal by means of high temperature. It mainly includes incineration method, vacuum cracking method, microwave method and so on.
2. Chemical method
Chemical treatment technology is a process of cleaning, soaking and extracting through chemical solvents based on the difference in chemical stability of various components in the PCB.
3. Cracking method
Cracking is also called dry distillation in industry. It is to place electronic waste in a container and heat it under the condition of isolating the air, control the temperature and pressure, so that the organic substances in it are decomposed and converted into oil and gas, which can be recovered after condensation and collection. Different from the incineration treatment of electronic waste, the vacuum pyrolysis process is carried out in the absence of oxygen, so the production of furans and dioxins can be suppressed, the amount of waste gas is less, and the environmental pollution is small.
4. Incineration method
The incineration method is to crush electronic waste to a certain particle size, send it to a primary incinerator for incineration, decompose the organic components in it, and separate the gas from the solid. The residue after incineration is bare metal or its oxide and glass fiber, which can be recovered by physical and chemical methods after crushing. Gases containing organic components enter the secondary incinerator for combustion and discharge. The disadvantage of this method is that it produces a large amount of waste gas and toxic substances.
5. Physical method
According to the different physical properties of the PCB, it is recycled by physical and mechanical means. The process is as follows:
a. Crushing
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.
b. Sorting
Sorting is to achieve separation by utilizing the differences in physical properties such as density, particle size, electrical conductivity, magnetic permeability and surface properties of materials. At present, air separation and electrostatic separation are widely used. According to the different physical properties of materials, the separation purity of Dongying’s circuit board recycling equipment can reach 99%.
At present, the physical recycling method is the best recycling method for wasted circuit boards and is also widely used. This method has the least pollution to the environment, while it also preserves all the metal parts. If you are interested in waste circuit boards recycling equipments, please feel free to contact us.
