Abstract
Two technological obstacles have so far prevented a successful industrial closure of the silicon furnace: Clogging of the charge material due to process related SiO-condensation (today solved by stoking through open doors) Handling of unburned off-gas with tar components, SiO-condensate and other effluents, involving energy recovery, off gas cleaning and dust treatment. Today huge amounts of air are sucked in below the cover in order to cool and control temperature, 5-10 times dilution. Possible benefits by closing are t. ex. better HES, reduced emissions, lower off-gas volumes, smaller filters, and improved energy recovery.