Waste printed circuit boards (WPCBs) from discarded computers, motherboards, mobile phones and other electronics are high-grade secondary precious metal resources. Their gold grade is dozens to hundreds of times higher than natural gold ore, making PCB gold recycling a profitable and eco-friendly circular economy business. Our integrated process combines physical mechanical separation and hydrometallurgical refining to extract gold, silver, palladium, platinum, copper and other valuable metals from scrap boards steadily.
Pre-treatment: Physical Separation & Metal Liberation
Physical crushing and separation is the foundation of modern PCB recycling, with low investment and controllable pollution. The workflow starts with manual sorting and dismantling to remove easy-to-separate components. Then materials go through primary coarse crushing and secondary fine crushing. When crushed down to 80 mesh or finer, metal particles can be fully dissociated from epoxy resin, glass fiber and plastic substrates.
After crushing, magnetic separation removes ferrous metals. Next, air gravity separation and electrostatic sorting separate non-metallic powder and metallic concentrates. Electrostatic separation reaches sorting accuracy up to 99.9%, while air classification features large throughput and lower operation cost. This physical pre-sorting concentrates precious metals first, greatly cutting chemical consumption in the subsequent leaching stage.
Hydrometallurgical Gold Extraction
Gold stays stable and mostly exists in elemental form on PCB gold fingers and plated surfaces. Industrial gold leaching mainly adopts aqua regia leaching and cyanide leaching routes, each suitable for different feedstock and production requirements.
For aqua regia leaching: gold dissolves into acid solution and forms Au³⁺ ions. Before reduction, we carry out nitrate removal (nitrogen oxide stripping) by heating and adding hydrochloric acid repeatedly to lower acidity and oxidizing strength. After filtration, qualified pregnant gold solution is ready for reduction. Common reducing agents include ferrous sulfate, sodium bisulfite, sodium sulfite, zinc powder, iron powder, oxalic acid, formic acid and hydrazine hydrate. We test tail liquid with stannous chloride solution to confirm full gold precipitation; no purple color means gold recovery is completed.
Cyanide leaching is widely used for gold-plating waste and low-concentration gold-bearing electroplating wastewater. Gold in cyanide liquor is recovered via electrolysis, cementation or adsorption methods. For surface gold plating scraps, selective de-gilding approaches including molten lead stripping, thermal expansion delamination, chemical de-plating and electrolytic de-plating can strip gold layers while keeping base substrates reusable.
Pyrometallurgical Route (Alternative Option)
Pyrometallurgy covers incineration, pyrolysis and smelting. It can handle bulk mixed e-waste directly, yet it needs strict flue gas treatment. Compared with pyrometallurgy, the physical + hydrometallurgy hybrid line we promote produces fewer exhaust emissions and is easier to control wastewater and solid residues.
Advantages of Our PCB Gold Recycling Solution
- High recovery rate: Mature process for gold, silver, palladium, platinum, copper, tin and lead comprehensive recycling.
- Flexible configuration: Standalone physical separation line, or combined leaching & refining unit according to customer site and raw material supply.
- Resource circularity: Recovered copper, resin powder, glass fiber can be sold as by-products to lift overall profit.
- Lower carbon footprint: Recovered metals from e-waste save mining, ore dressing and smelting energy consumption, cutting waste discharge drastically.
Raw Material Scope
Our recycling system fits waste computer motherboards, graphics cards, server boards, scrapped mobile phone PCBs, gold-plated connectors, electronic plating waste and other gold-bearing electronic scraps.
If you are looking for reliable equipment and process guidance for e-waste precious metal recovery, welcome to contact us for customized flow design, plant layout and technical support.
