Electronic waste includes waste products, scraps, and discarded printed circuit boards from the manufacturing of electronic components and parts, as well as obsolete computers, appliances, and mobile phones. Every year, millions of computers, televisions, and other household appliances, and tens of millions of mobile phones are discarded, containing significant amounts of precious metals. Roughly estimated, 5 million computers contain approximately 4.2 tons of Au, 30 tons of Ag, and 1.5 tons of Pd. 50 million mobile phones contain approximately 140 kg of Au, 1 t of Ag, and 50 kg of Pd, totaling 4.34 tons of Au, 31 tons of Ag, 1.55 tons of Pd, and a small amount of Pt. This represents a substantial amount of resources, and many small businesses and workshops in China are actively engaged in recycling. However, the primary focus of electronic waste recycling is on Au, Ag, Pd, and Pt, with the latter accounting for only a small percentage of the total secondary resource recycling volume. From the point of circular economy, these discarded electronic waste still has the very high value.

Electronic waste is characterized by its large volume, low-grade precious metals, and complex composition, containing significant amounts of Cu, Sn, Pb, as well as bakelite and plastics. Workshop-style recycling primarily uses incineration to decompose bakelite and plastics. The slag is dissolved in calcined acid or aqua regia, and precious metals are then separated and recovered from the solution. This method has low material utilization and precious metal recovery rates, and causes severe environmental pollution. We have mature and environmentally friendly recycling technology and professional recycling plants.