The Waelz process is a method of recovering zinc and other relatively low boiling point metals from metallurgical waste (typically electric arc furnace flue dust) and other recycled materials using a rotary kiln (waelz kiln).
Subsequently, the Dedpolph patent was taken up and developed by Metallgesellschaft (Frankfurt) with Chemische Fabrik Griesheim-Elektron but without leading to a production scale ready process.
[4][3] Kiln size is typically 50 by 3.6 metres (164 by 12 ft) long / internal diameter, with a rotation speed of around 1 rpm.
[3] The process also captures other low boiling metals in the waelz oxide including lead, cadmium and silver.
[6] Increased use of galvanised steel has resulted in increased levels of zinc in steel scrap which in turn leads to higher levels of zinc in electric arc furnace flue dusts.