Designing Gas Cleaning Plants for E-Scrap Recycling Furnaces

Whether top-blowing rotary converters, top submerged lance smelters, or other smelting processes are used for converting WEEE (electric and electronic waste, computer scrap) or mixtures of slag from copper smelters with electrowaste and/or computer scrap to recover copper and other precious metals, an off-gas treatment is required to ensure an environmentally clean process. The off-gases from these furnaces differ from the usual gases of primary smelters, as they often contain a very low load of SO₂ (thus, a sulfuric acid plant is not an option) but very high loads of hydrofluoric acid, hydrochloric acid, hydrobromic acid, and bromine. Further, some processes may carry high mercury loads. For environmental compliance with specific clean gas requirements, multistage gas cleaning trains and advanced materials of construction may become necessary. In this paper, GEA presents different treatments of these off-gases as well as key performance values. Besides the equipment of a typical gas cleaning train for primary copper smelters, which consists of hot electrostatic precipitator, scrubbers, and packed cooling towers followed by wet electrostatic precipitators and often mercury removal technologies, additional equipment for halide removal as well as advanced material concepts to deal with corrosive halides will also be explored.