Three high temperature processes of the electronic waste processing: smelting/incineration, pyrolysis and gasification were shortly discussed. The most distinctive feature of electronic waste is complexity of components and their integration. This type of waste consists of polymeric materials and has high content of valuable metals that could be recovered. The purpose of thermal treatment of electronic waste is elimination of plastic components (especially epoxy resins) while leaving non-volatile mineral and metallic phases in more or less original forms. Additionally, the gaseous product of the process after cleaning may be used for energy recovery or as syngas.
Steam gasification seems a promising technology of waste transformation since the steam is the only oxidizing reagent in the process and gaseous carrier of volatiles. Gasses are equilibrated at high temperature for conversion to the H2-rich syngas. After this step, the excess of steam condenses during cooling, together with non-converted tars, oils and fine particles. Condensing steam efficiently absorbs hydrogen bromide and hydrogen chloride. The use of steam eliminates carbonaceous residue from the solid mineral/metal product, which is convenient for further processing (for example extraction of metals). The syngas and the solid residue are generally the only products of gasification, because aqueous condensate may be returned to the process together with non-volatile hydrocarbons and sediments. The process was illustrated by laboratory scale gasification experiments with a) carton packaging, b) abrasive disc, c) pork bones, d) Cu multiwire cable e) PC/AT card and f) inverter (PCB board). The mineral/metal products of gasification may be considered as a raw materials for further processing, including typical routes of metals recovery. There is no direct emission to the atmosphere from the process. However, providing the energy from the syngas back to the reactor as well as the energy balance of steam condensation and recirculation of condensate to the reactor need careful analysis.
PCBs (Printed Circuit Boards) are important parts of electronic equipment and their use increases with technology development. Recycling of waste PCBs is challenging due to their complex structure and receives wide concerns as the amount of this type of waste is growing rapidly. In the article, the experiment of pyrolysis carried out with electronic waste sample was presented. The material employed in the present work was inverter of the LCD screen that it the example of the multilayer PCB. The correlation between pyrolysis temperature and gas emission from the system, which is associated with epoxy resin decomposition, is presented in the article.