Treating sludge obtd. in cleaning blast furnace throat gas - for reclaiming reduced iron oxide(s) and valuable non-ferrous metals

摘要

The sludge is fed into a tank in which lime is added to adjust the ratio (CaO + MgO)/SiO2 of the solids to 1.2-1.5, followed by settling and removing part of the water. The wet residue is mixed with granular carbon, and fed as a damp. mixt. contg. 45-55% water into a rotary drum furnace. In the furnace, the mixt. is dried and heated to 900-1300 degrees C for at least partial redn. of the iron oxides and agglomeration to obtain a prod. which can be added to the charge fed into the blast furnace. After settling, the sludge is pref. filtered and washed, then mixed with coke grit with size up to 10 mm. The furnace pref. uses an oxidising atmos. so Pb and Zn are volatilised and can be recovered from the gas leaving the furnace.