Efficiency of leaching of used PCBs using different acids

Today, waste of electrical and electronic equipment is a big problem because it contains heavy metals such as copper, cadmium or nickel that cause neurological diseases. In addition, such waste also contains precious metals such as gold and silver, which makes this material really attractive for recovery. One of the fastest-generated groups of electrical and electronic waste is mobile phones. In 2008, the global sale of smartphones reached the level of 140 million units, while in 2015 it is rapidly growing to the level of 1500 million units. The lifespan of phones is also shortened to 8-12 months, which means that in the near future the number of mobile phones will continue to grow. The generated amount of electronic waste, including mobile phones, supports the search for an effective way of processing this waste. The dominant materials in used mobile phones are printed circuit boards (PCBs), which consist of a non-conductive substrate or laminate, conductive copper substrate printed on a laminate or inside a laminate and components attached to the substrate (chips-Ga, In, Ti, Si, Ge, As, Sb, Se and Te), connectors (Au, Ag) and capacitors (Ta, Al). Economically, the most important metals that can be recovered are copper, gold and silver. There are many methods to recover such metals based on pyrometallurgical and hydrometallurgical processes. Hydrometallurgical methods used to recover metals from electronic waste have many advantages over other methods. The paper presents an overview of hydrometallurgical studies of metal recovery from PCBs using various acids. Furthermore, the results of the leaching of printed circuit boards of used cell phones with H₂SO₄, HCl and HNO₃ are presented. Research focused on the recovery of metals such as copper, iron, zinc, tin, aluminum and nickel.