Removing heavy metals, esp. mercury from contaminated earth - by repeated washing and fractionation forming conc, fraction for furnace

摘要

Soil, building rubble or other bulk material contg. heavy metal contaminant, esp. Hg, is initially washed and sieved to produce a finer fraction with enriched metal content. After removal of existing water, this fraction is homogenised by feed water and rewashed in a process combining gravitational and centrifuged feeding, without external power supply. The resulting fine slurry is thermally treated, e.g. in a vertical furnace with multiple superimposed hearths, at temp. appropriate to the particular contaminating metal, with furnace construction modified if necessary. The furnace exhaust gases pass via a venturi washer to a droplet separator collecting the heavy metals. ADVANTAGE - Effective sepn. involves min. power consumption.