Mass balance of mercury in a pilot scale mercury recovery plant using thermal roasting technology

Özet

A pilot scale mercury recovery plant was developed to treat Hg waste by thermal treatment. The capacity of thesystem was 60 kg/batch and consisted of four units carrying out thermal treatment, dust separation, con-densation, andflue gas treatment. The mass balances of Hg fromfive different wastes in three categories werecalculated from Hg recovery data. From the following selectedfive wastes, Hg-added product, Hg-contaminatedsoil, byproduct offluorescent lamp treatment process, and waste sludge from non-ferrous metal industrialprocess, we recovered 97.5%, 83.61%, 93.07%, 70.25%, and 29.36% of elemental mercury, respectively. Dustinterfered during the condensation process, as volatilized Hg vapor was condensed with dust. Hg concentrationsin leaching extract of treatment residues from the Hg-added product, Hg-contaminated soil, and the byproduct offluorescent lamp treatment process were 0.003 mg-Hg/L, 0.0045 mg-Hg/L, and 0.002 mg-Hg/L, respectively,which are below the Korean classification standard of hazardous waste for mercury (0.005 mg-Hg/L). Hgconcentration influe gas was lower than 15μg-Hg/m3after passing through the activated carbon trap.Byproducts of the pilot scale system, such as activated carbon and dust can be further treated and converted toHg free waste.