Zero-waste metallurgy

The project "Zero-waste metallurgy" developed a process which allows auto thermal metal recovery from WEEE scrap. WEEE stands for "Waste Electrical and Electronic Equipment", i.e. disused electrical equipment, which will continue growing as a consequence of the increased demand of information technology (IT).

Electronic scrap is an important secondary raw material which contains several valuable metals. However, the currently existing metallurgical recycling methods are inefficient due to the huge amounts of energy required, increased metal loss as well as waste generation.

The project developed a continuous process for recovering of valuable metals from complex mixed waste materials with a high plastic content. In this novel process the electronic scrap is put into a furnace which can be tilted and rotated. Oxygen is blasted onto the material to be melted while the furnace is being rotated at high speed. Tests have shown that auto thermal melting is possible because of the combustion of the organic materials already contained in the WEEE scrap which cover the respective energy demand: The process temperature can be maintained for hours or even increased slightly without the use of additional fuel.

The new process yields to three main products: a molten metal phase with high copper content besides other accompanying elements such as silver, gold, nickel, lead, tin and antimony. This rich copper phase can be added to a conventional refining process for copper via anode furnace. A Mineral phase is also produced containing a low concentration of precious metals as well as flue dust with high percentage of lead, zinc and halogen elements. This single stage process without expenditure of fossil fuels avoids waste generation and improves the efficiency of recycling compared to traditional WEEE recycling processes found in the state of the art.