RECYCLING OF PRINTED CIRCUIT BOARDS BY ACID LEACHING

Currently, an avalanche of technology development can be observed, which results in an increase in the production and sale of electrical and electronic devices. The lifetime of electronic components, which at the end of the 20th century was 4 to 6 years, was shortened to 2 years in the first decade of the 21st century, and even to 9 months in the case of mobile phones. Today, most electrical and electronic devices contain printed circuit boards (PCB). On the one hand, PCB with electronic components is a hazardous waste due to the content of toxic components, on the other hand, it is a source of many valuable elements, including precious metals, non-ferrous metals, rare earth metals, platinum group metals, as well as iron and silicon. The metals in PCBs can be present in much higher concentrations than in conventional ore deposits, making PCB waste a particularly interesting material for recycling. PCB recycling involves multiple steps using a combination of physical, chemical, thermal and metallurgical processes. The main methods of recovering metals from PCBs are pyrometallurgical and hydrometallurgical methods. Hydrometallurgical techniques largely involve acid leaching, which has many advantages including high leaching rate and fast kinetics, but is quite corrosive. In laboratory tests, mineral acids (H2SO4, HNO3, HCl) as well as aqua regia are used for leaching, sometimes with oxidants. The article reviews interesting and effective methods of leaching printed circuit boards from used mobile phones in the context of recovering copper and other metals contained in this waste.