As we all know, Pyrolysis is a technology used to dispose plastics, which can also be used to recover thermosetting composites and heat and pyrolysis waste circuit boards in the absence of oxygen or oxygen. When waste circuit boards are heated to 300-900 ℃ in reactor, chemical bonds in high molecular organic polymers such as epoxy resin and phenolic resin begin to break and convert into low chain hydrocarbons, resulting in liquid and gaseous products. Organic substances (such as pyrolysis oil) have a high calorific value and can be used as fuel or as chemical raw materials after subsequent treatment. The metal parts, inorganic substances, and other solid products in the residue are further processed for separation.
Solid products, gas products, and liquid products were obtained by pyrolysis of computer circuit boards, with product yields of 68.9%, 4.7%, and 22.7%, respectively; 60.0% of solid products, 6.5% of gaseous products, and 28.5% of liquid products were obtained by pyrolysis of TV circuit boards; 82.2% of solid products, 2.3% of gaseous products, and 15.2% of liquid products were obtained from pyrolysis of mobile phone circuit boards. The content of liquid products and total phenolic substances is relatively high (with the highest content of phenol), in addition to which there are more organic phosphorus compounds. Solid products include easily separable metal components, glass fibers, and other organic and inorganic substances. Ash is mainly composed of calcium, iron, copper, nickel, and aluminum, as well as lower concentrations of precious metals such as gallium, silver, and gold, with a higher silver content. The main components of gas products are CO2 and CO.
Pyrolysis can separate organic and inorganic substances, with simple operation and fast reaction process. Pyrolysis can significantly reduce the generation of dioxins, resulting in fewer harmful substances generated during the treatment process, and high resource recovery rates, especially for tin, lead, aluminum, and magnesium. This method has many industrial applications in China, and pyrolysis technology has great potential for disposing waste circuit boards.
